2001 jeep cherokee sport misfire in cylindewr 3, engine light stays on car sputters occaisionally and often stalls

P0303 JEEP - Cylinder Misfire Fault Detected - Possible causes Faulty spark plug 3 Clogged or faulty fuel injector 3 Faulty ignition coil 3 Fuel injector 3 harness is open or shorted Fuel injector 3 circuit poor electrical connection Ignition coil 3 harness is open or shorted Ignition coil 3 circuit poor electrical connection Insufficient cylinder 3 compression Incorrect fuel pressure Intake air leak... The P0303 code means that the cylinder 3 is misfiring or is randomly misfiring. Start by checking for intake leaks an if no leaks are found the next step is to replace the spark plugs on cylinder 3. If the problem persist more tests needs to be done to diagnose problem.

I've had the same problem for a couple weeks now in my '01 grand cherokee. sporadic missing while driving-hot or cold but when I hit 35-40 mph it seems like the engine is bogging down (accelerating over 40 is fine) and after a few times of hitting 35 - 40 mph the bogging gets worse and then choking and stalling is guaranteed. once the bogging down starts and progresses I prepare for the choking and stalling. I've replaced the spark plugs, ignition coil, cam and crank sensors and o2 sensor. ANYONE HAVE ANY CLUE????? interesting note....coil was the last part to be changed. jeep drove great 2 days after but then started missing and back to the cycle above.

I see I missed some commas in my last post, Check for intake manifold leaks.

i have a 99 4.0 and cyl. 3 is miss firing but i get spark, fuel and theres no vac. leaks. i did the rings and inspected the valves but nothing was visable when rebuilt. i will be tearing it down and doing a full rebuild again if i have to.