Fuel Injection Recently I used spray throttle body cleaner and flushed the butterfly valve in the throttle body. The area around the butterfly valve was very dirty. I added fuel injection cleaner to the fuel. I picked up ~1MPG but the car struggles at low RPM under load, jetting/stalling. Most of the time around 40mph when feathering the throttle or off the line. It seems to be fine over 2000RPM and at idle. Stuck or clogged injector? Fuel filter? Throttle positioner? Ideas?

Not sure if this will help but i had a similar problem on an 85 Lincoln Town car right from the first week i bought it, hitting the dealership for warranty almost weekly because of this problem it took them 2 years to figure out it was a problem caused by built up carbon particles that were getting lodged in the EGR valve which was cone shaped, there by not allowing the valve to close properly and giving a false sensor reading to the engine and causing it to shut down, Once the ignition was turned off it would start again and run normally for anywhere between a few hours to a few days then do it again. To solve the problem they custom built a small screen to go in front of where the intake line to the EGR is and that seemed to solve the problem. I was told it had happened to other Ford and Lincoln vehicles as well with the V8 throttle body injection fuel system.

1. Purchase "02 Sensor Safe" throttle body cleaner spray;
2. Drive the vehicle a few miles, bringing it to full operating temperature, then park it in your driveway with the engine still running;
3. Gain access to the throttle body, and hold your thumb on the butterfly linkage so that you can open the throttle butterfly when the engine begins to load;
4. Begin by spraying throttle body cleaner spray on all linkages around the throttle body. If the engine begins to bog because it is aspirating throttle body cleaner, quickly open the throttle butterfly to keep the engine running.
5. Once you have cleaned all around the throttle body, spray cleaner DIRECTLY INTO THE THROTTLE BODY, opening the throttle sufficiently to keep the engine running. It will run rough during this process but try not to let the engine stall.
6. If the engine stalls, restart it, and continue cleaning the throttle throat until you see clean metal.
7. Pour some fuel system cleaner into the gas tank and drive the car a little more before parking it. Try to find an excuse to accelerate hard, WIDE OPEN THROTTLE momentarily if safely possible (as when accelerating to merge into traffic on a highway).
8. Drive back home.
9. Done.

The throttle body needs to be cleaned, grime in this area prevents the throttle plate from closing completely and allowing air to enter, making the air/fuel mixture lean. Make sure to clean the front and back sides of the throttle body. Also, disconnect the battery during the cleaning process to allow the computer to reset and relearn to the cleaned throttle body.

spray the throttle body with throttle body cleaner, use the whole can on it until the butterfly and surrounding area is spotless

TOOLS NEENED ......
FLATE BLADE SCREW DRIVER/STAR SCREW DRIVER/10MM/ QUARTER IN DRIVE RATCHET WITH 5 INCH EXTENTION/CARB. CLEANER OR INTAKE CLEANER/LAXTEX GLOVES./ TOOTH BRUSH
SPECIAL TOOLS REQUIRED ( AIR COMPRESSOR) WITH BLOW GUN
WEAR SAFETY GLASSES WHEN PERFORMING THIS TASK!!!!


START BY CHECKING ALL VAC. LINES/HOSES
MAKING SURE ALL IS CONNECTED.

IF ALL LINES LOOK AS IF THERE FITTED OK.
NEXT REMOVE AIR INDUCTION SYSTEM , THIS IS THE PARTS START
AT AIR FILTER BOX AND IS FITTED TO THROTTLE BODY.
REMOVE THIS PART( THERE WILL BE A WIRE GOING TO THIS PART(MASS AIR FLOW SENSOR) CARFULE NOT TO DAMAGE, UNCLIP WIRE GOING TO SENSOR.
NEXT LOOK IN SIDE THROTTLE BODY NOTICE THERE IS A BUTTERFLY TYPE PLATE.
YOU WILL NEED TO PROP. THIS PLATE OPEN , THIS IS DONE BY USING YOUR FINGER(CAREFUL NOT TO HURT YOUR SELF)
YOU CAN USE A SCREW DRIVER TO HOLD OPEN BUTTERFLY
MAKE SURE YOU DONT USE A POCKET SCREW DRIVER , YOU NOT WANT IT TO FALL IN THE INTAKE SYSTEM.
YOU MAY NOTICE THAT THERE IS A SMALL HOLE NEAR BUTTERFLY
TAKE CARB./INTAKE CLEANER AND SPRAY IN THROTTLE BODY/BUTTERFLY/SMALL HOLE.
TAKE SOFT TOOTH BRUSH AND LIGHTLY BRUSH AROUND BUTTER FLY AND AROUND MATING SURFACE OF BUTTERFLY, USE CLOTH TO CLEAN CARBON ( TRY TO GET THIS CLEAN AS YOU CAN , USE CARB. CLEANER.INTAKE CLEANER THREE OR MORE TIME.( ALSO SPRAY IN WELL VENTALATED AREA.
AFTER CLEANING REALLY WELL !!!!!
TAKE AIR LINE WITH BLOW GUN AND BLOW OUT THROTTLE BODY, MAKING SURE YOU GET ALL OF THE CLEANER/CARBON OUT.
ALSO BLOW IN SMALL HOLE( NOT DIRECTLY ON HOLE BUT NEAR HOLE.
NEXT STEP. IS TO PUT AIR INDUCTION HOSE BACK ON , MAKING SURE YOU PUT HOSE OVER THROTTLE BODY AND SECURING WITH FASTENER AS WELL AS OTHER END GOING TO AIR FILTER BOX.
RECONNECT ALL VAC. LINE/HOSE TO THERE ORIGNAL LOCATION
RECONNECT WIRE GOING TO MASS AIR FLOW

NOW TRY STARTING VEHICLE , MAY TAKE A FEW TIMES TO CLEAR
ALL THAT CLEANER THAT YOU SPRAY IN INTAKE.
IF RUN , YOU MADE A FIX!!!
IF STILL HAVE A PROBLEM MAY HAVE PROBLEMS WITH MASS AIR FLOW SENSOR.
GOOD LUCK!

Try cleaning the throttle body. Use a throttle body cleaner and do not flood the throttle body with the cleaner. You will have to open the throttle up and spray around the butterfly. It most likely carbon buildup and causing the butterfly to stick when you accelerate. A couple of short sprays will be fine, clean with a cloth. You will see a lot of black buildup flow out of the throttle body. After you wipe dry, let the intake hose stay off for a few minutes for the throttle to dry out.

Check the IAC valve (idle air control) might be dirty and sticking. Remove air intake hose to engine, spray throttle body cleaner in upper right opening in throttle body to clean, also spray all areas of throttle body while opening and closing butterfly, then start truck and spray IAC valve and openings while running. If that does not work replace the IAC valve with new one.

Try this: Go to your local parts store and purchase a can of (throttle body cleaner) you will take your air filter out and remove the big tubing that is connected to your throttle body and filter housing. Spray the cleaner inside the throttle body, open the (butterfly) and spray around the pivot the butterfly opens and close on. What happens is you get carbon build up in these areas and it causes the gas pedal to feel like it's stuck and have to apply more pressure to the pedal. You will see alot of black carbon run out of the throttle body. Take a clean rag and wipe down the area of the throotle body. Repeat the cleaning 1-2 times. put your air inlet tubing back on and re-install your filter. It may seem hard to start at first but it's drying out the cleaner that was sprayed inside the body. Try this and see if this works. I've done this on many vehicles that shops want to charge $300 to do and all you need is $5 cleaner. It's very easy to do and takes 20 min.

Try cleaning the throttle body, especially around the butterfly pivot pin, and the area where the butterfly sits in closed position. Over time, these areas are bad about carbon build-up. Once carbon gets built up, the butter fly can't completely close, which causes the throttle to still be open a little. This can cause higher idol (rpms). Very simple process. Buy throttle body cleaner for $6, remove your air intake hose from the intake. open your throttle and you're see the butterfly open and close. Spray the inside of intake, butterfly. You're see a lot of black carbon run out. wipe clean with a clean cloth. Repeat 2 more times until you don't see carbon running out. Put your intake hose back on, and you may have to turn the engine over a few times to dry the cleaner out. It's gonna sound like it don't want to start, but once the cleaner is dry, it will start and hopefully, this will solve your problem. Also, look at your throttle cable for any hoses, wire or anything to prevent the cable from closing the throttle.

I had same problem with Scion. Took it to a Mobil One quick oil change place. Flushed injectors. It was under $100 and ran like new.