1988 f150 custom 302 efi. Let me give a little side story. Bought the truck and needed lots of work. Pulled motor and did a rebuild. Comp cams 268h w/ matching lifter set, water pump, timing chain, timing cover, 4 hole 215cc bosch 19lb injectors, block honed and cleaned, heads have comp cams upgraded springs, perf valve grind, long tube headers and more. Fired truck up and ran great. Decided to pull the engine codes and popped up MAF sensor out of range. Bought a new map senson and truck runs like a beast on the road but wont idle worth a dang. Un plug new map and swap with old map and idlea great but the afr is off. I have confirmed there is NO vaccum leaks. Replaced throttle postion sensor and still idles crappy. Ive invested alot of moeny into this rebuild and cant hunt down this efi idle problem. Any help would be great. Thanks

 

What are the exact code numbers are you getting? It will never idle like stock with that cam.

 

Ive got a code 22- map sensor out of range, code 31-egr sensor out of range (egr deleted) and a code 96- fuel pump curcuit open, battery to pcm. I just want to figure out why its hunting to find idle at a stop but runs great on the road. Ive also got a slight shudder/miss when im barely touching the gas. Thought maybe timing was off, nope set at 10 btdc. Running on 93 pump gas thinking it would help but no. Only thing i can think is the truck cant keep up with the cam at idle

 

Could it be possible that when the bad map sensor is installed it is making the computer throw more fuel in than needed at idle to keep it going and when the new good map sensor is installed its making the truck run the way it should and afr ratios are off? At this point I'm leaving the bad map sensor in until I can figure out why it wont idle with the new one.