My truck hesitates at low rpms and even in 5th gear it stumbles a little just cruising. It's a 94 4.0 and the check engine light comes on after I have started driving it for about 5-10 minutes. I have changed both o2 sensors all the spark plugs and wires and fuel filter. I was told it could be the ignition coil or the catylitic converter could be stopped up. Please help!!!!!

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Also it will not hesitate if I hold the gas all the way down. It hesitates and stumbles until I floor it then it stops until I change gears again

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94 4.0 ranger/5-speed/296,000 miles

At WOT the system goes into open loop. Some sensors like O2 sensors are not used in open loop.

1999, Reg Cab, 2.5, 5 speed, 145k. (Sent from my DROID BIONIC using FRF App)

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2004 Ext Cab, 4WD, 4.0, Auto, 154k. (4.0 engine is out of a 2009 Ranger w/96k) ( as of 7/1/2017)

2004 Ranger, Ext Cab, 2WD, 3.0, 5 speed , 4WABS, crank windows, no cruise, Edge 116k.(6/5,2014) (SOLD).
1999 Ford Ranger, Reg Cab, 2.5, 5 speed, 2WD, no AC, 150k (SOLD).

Have you checked for codes in the PCM? If the check engine light comes on then there should be codes stored even though it turns off when you restart it.

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1999 Ford Ranger XLT, 4 dr supercab, 5-spd manual, 4.0 OHV, 4x4, FX4 Shifter, 2004 Ranger front end conversion, 2009 Ranger tail lights, Volant cool air intake.