I have a 2007 f150 with a 5.4. I am having an issue with a stumble under load. Idle is good, but if you torque it up in drive with brakes on it pops and stumbles. I have no engine light during this.

Weird thing is, if I go about 70 km/h and give it about 1/4 throttle, it misses and shudders violently. If I do this long enough the engine light will come on, and flashes. But by the time I pull over to plug in my code reader, engine light is gone. Also, under WOT, it hesitates until about 4000 rpm, then winds up like it always did

Any help would be fantastic. I should also point out that in the summer (it's winter here now) if working the engine hard, it has that awesome issue where the engine rattles, shakes, and knocks at idle

 

a flashing CEL indicates a mis fire...could be a plug/COP/injector/FPDM/clogged cat...you did not say the mileage on your truck...this would help...first thing I would check is the condition of your FPDM mounted under the back of your truck by the spare tire, they can get severely corroded to where the back side of the module is exposed...very common problem.

 

Ok so I managed s to get codes. First it started as a cylinder 3 misfire. Checked COP for spark, is good. Pulled spark plug, broke off at porcelain. Used a JET porcelain remover kit, then the JET shield extractor kit. Replaced plug, put it together, was solved for about 10 mins.

Same stumble reappeared, got a code, cylinder 4 misfire now. WTF? COP is good, broke spark plug again. Same process, put it together.

Same damned thing. You said the driver module could be culprit? I've changed some in the past, bit that was to fix a no-start. They can cause this?

 

Sorry it's got 17300 kilometers

 

2007 F-150 4.6L engine with 232,000 miles on it.Okay! Okay! Okay!I have found the source of the shutter/stumbling. For my truck, it was the intake manifold that did it to the truck. The antifreeze leak over into the spark-plug shafts and cooked to a goo! This goo caused the coils to arc against the block, versus going through the sparkplug into the chamber. The unburned gas passed right into catalytic converters. This caused them to burn super hot and destroyed the catalytic converters substrait to where they became block. Once the catalytic converter’s O2 sensor detected a high and steady stream of unburned gas, it puts the transmission into limp-mode. In limp-mode, it does not allow the transmission to shift properly and definitely will not allow it to get into overdrive. I had wrestled with this problem for a few months. I replaced all coils/two injectors/all sparkplugs/air-filter/MAF sensor/all of the exhaust (excuse to get duals {semi}). I picked up the truck today with from the shop with (semi) dual exhaust on it. The truck runs like it is brand-new and it sounds great. I can set a glass of water on the hood and barely a ripple. The passenger seat does not rattle like it used to do. Next to be replaced is the intake manifold (the slow leaks that caused it all). I hope this helps.