I bought a 2006 Dakota 3.7L 6 speed off my dad and had to put an engine in. Only difference with the new engine is it doesn’t have an EGR system but never any codes for it. Last one lost all compression for some reason. Drove it down back roads for a minute for the computer to re-learn with the new engine and it seemed soggy then but it had a misfire and all sorts of codes while learning. I assumed the doggy-ness would pass.

Codes cleared up and was fine for a week before I got an 02 code. I put in iridium plugs and did the O2 sensor. Still feels like I’m driving with the parking brake partially on. I just read on another forum that apparently with plugs for these they’re pretty much never gapped to what they’re supposed to be and an inconsistency between the gaps would cause more of a problem than wrong space gap all across. Which I didn’t check the gap because I never had a problem before with plugs not being gapped properly. Kind of regret that decision.

Since doing the plugs and O2 sensor I’ve had an Evap System code (not one that specifies anything), Catalyst below efficiency code and half the time “9ASCAP” in the odometer. I have replaced the gas cap. I don’t remember the code numbers but I can try getting them if need be.

I’m lost on why it’s acting like I’m driving with the parking brake on (loose and barely works when engaged and tired aren’t affected by it when rear is lifted with parking brake off) and sometimes I can go through a quarter tank in 20 miles of basically no stops. I haven’t had any luck with Google or Facebook groups regarding my problems.