96 regal 3.8 liter missing at above 3000 rpm, stumbles and wont go over 4000 rpm. changed plugs and wires, coils,and checked all injecters,seem to be all functioning.changed fuel filter too.no check engine light on.do not have scan tool. any suggestions?

Ford coil on plug systems are multi strike ignition (spark) under 1300 rpm then go to single strike a single cylinder misfire can be created by several things . #1 Test engine compression on a cranking engine compression it should be around 150 lbs but if gauge reads different COMPARE to other cylinders that work fine #2 check engine running compression this will be around 120 lbs then rev over 2000 rpm and check pressure drop again COMPARE to other cylinders that work fine. any drop would indicate valve train problems. #3 All internal engine is fine then external problems are present vacuum leaks and or fuel injection volume is low.

check the fuel pressure and the fuel filter. You've eliminated the ignition probables.

It sounds like you may have a small block in your fuel system. When was the last time you changed your fuel filter out?

p0303 is cylinder 3 misfire. Check that plug, boot and coil. . You can move this coil and boot to another cylinder to see if the code changes. If it does, you have a bad coil or boot. Its most likely the spark plug boot on cyl 3.

Hi Tom your vehicle is equipped with a Rev limiter it will not allow you to rev the engine above 4000 with the trans in park; as for the first problem you may have one of two things, one of the spark plugs or spark plug wires is bad or you have a flat spot on the throttle positioning sensor in which case have be replaced. Good luck?

Did it spark well on all the plugs? Usually if you have no change in idle with two wires removed it needs a new set of spark plug wires. If it was cylinder 2 & 3 (side by side) then you should suspect a head gasket. Does the Bronco have multiple coils or a coil pack with multiple inputs? Are these two plugs hooked up to one coil?

Has anyone checked your "rev limiter" ? It is a sensor that will not allow you to "rev" your engine past a cetain RPM.
It is usually only "on" when you are in PARK, but it is something to consider.
Please let me know what you find.

4.3L for some reason tend to have problems with the fule pressur regulator. its a smoll round metal valve. you will fined it on the driverside fuel rail. also replace your fule filter and run an injection cleaner through the tank. hope this helps.

try changing the coil packs

Could be a short in the wiring for the O2 sensor.   I currently have the same issue only my car finally threw a code after two days of it acting up.  Code 106.  Changed the MAP sensor and it now throws 108, MAP sensor high voltage circuit.  Ah the joys of cold weather and broke down vehicles.  But I know that you wont always get a code with a short.  Let me know if you fixed the problem.