I have a 97 f-150 flare-side with the 4.2 V6. My truck is not throwing a code, and runs fine. However, whenever I really drive it hard (pulling out in traffic or merging onto the highway) the engine bogs down and bucks when I get to about 2800-3000 rpms. replaced the TPS and checked for vacuum leaks, but still hasn't fixed it. Does anyone have any ideas?

 

It doesn't have any issues in first gear or neutral, only in 2-5.

 

How new or old is the spark plugs, wires, coil packs? Maybe a cleaning of the MAF sensor, t-body and IAC are needed. Mine kinda did similar, runs like a champ now. Running on the freeway w/o overdrive pulling a 5000 plus lbs covered car trailer with premium gas probably didn't hurt either. It burned ALOT of crap out that day I'll bet, especially going 60-65 mph.

 

At that RPM, it almost sounds like a IMRC problem - that's about where it opens.

 

True true, maybe just gummed up with carbon crap! Usually I find they fail stuck open I'd guess but this one could be on it's way. Pretty common on the v-6's.

 

Thanks for the help! It jjust started throwing a code for a gross evaporated leak. Going to diagnose that. Any chance that could cause my issue?

 

What number is the code?