I have a '97 Ranger 4.0L. Recently my check engine light went off. Both sides of the engine are running lean and rich. So four codes total. Not sure how this is happening because they are contradictory codes. I have a cold air intake and custom exhaust. Besides that i have replaced the wire hareness, replaced both MAF and EGR, cleaned out injectors, ran compression and smoke tests, and all that fun stuff. Any ideas on what could be pushing these codes?

 

o2 sensors?
my guess would be on faulty sensors/wiring

 

check your scaling tables - that will give you clues.

wasted money on a cai, because your truck came with that from ford.