I have a 1990 Ford F150 fuel injection and it idles to fast.

the best advice i can offer is to check for air leaks when cold ,if anything else then you may need a remap or something .

Sounds like a vacuumed leak, spray wd40 around the inlet manifold whilst on idle

First thing to try would be different fuel. Use a fuel stabilizer and fill with good gas. see if that helps. Also, check the fuel pressure.

fuel injected motor. not adjustable. if idling high, replace throttle position sensor. fixes that problem 90 percent of the time.

YOU CAN PUT THE TIMING BACK TO ORIGINAL POSITION! ON TOP OF THE MOTOR! IF IT IS CARBURATED, YOU CAN ADJUST THE IDLE SCREW TO RAISE IDLE! IT WILL BE A SMALL SCREW LOCATED BEHIND THE THROTTLE PLATE! ON FUEL INJECTED MOTOR, IT IS LOCATED UNDER THE COVER WHERE THE THROTTLE CABLE GOES INTO! YOU WILL SEE A SMALL SCREW BEHIND THE THROTTLE PLATE! THE PLATE IS A RECTANGULAR PLATE THAT YOU CAN MOVE TO INCREASE THE IDLE BY HAND! I OWN A 93'!

Here are a few things to try. You could be venting vacuum with a bad intake gasket. Use a spray bottle with water and go along the seams with the engine running to see if you can find any openings. The engine will change RPM if it draws in water.

Autozone or Oreillys will check the engine free with a scanner. Usually a TPS throttle position sensor will code a "check engine" light and a manifold leak won't. The TPS is like a carburetor and controls spark and fuel as it works. It is cheap and simple to replace.

yes they should be cuz it is the same truck

I Have a 1999 ford f150 4.6 that back fires and is just running really ruff when idling alot of nack fire a sord of like a pulse going on what is my problem?

Having the proper thermostat in fuel injected vehicles is very important.They have a engine coolant sensor to tell the computer the temp of the coolant. If the engine is running too cold,(or cold all the time), the computer is going to tell the idle motor to raise the idle and to give it more fuel, which can damage the cat converter. These vehicles need a 192-195 degree thermostat. Also check the TP sensor (throttle position sensor for proper voltage) the green wire should read .7 to 1.00 volts.

Those Fords Have Problems With The IAC(Idle Air Control Valve) On Top Of Intake By Throttle Body. It Might Even Be Making Some Weird Noises? If Not Check Timing, And Fuel Preasure.....Check For Vacumme Leaks. Good Luck