Ok, this is a cheapie truck. And I am trying to keep it that way. I bought it year ago with worn out clutch. Started fine and engine sounded good. I knew nothing about this generation Ranger. Replaced clutch myself. Drove but tranny pretty noisy and would pop out of first, and fifth screamed like banshee. Seller hadnt mentioned this of course. Mr. Lucas quieted it down. Then got hot stall at idle, though usually will drive fine down hiway on shorter trips. It will bog down noticably on longer drive where lucky to get it over 40mph on a hill. I finally got rpm I wanted and unplugged the IAC. Kept it at 750rpm cold or hot. Have to feather pedal cold but keeps from stalling at hot idle. Replaced oxygen sensors, fuel pump, fuel pressure regulator, throttle position sensor and couple other things. MAF looked shiney and new, assume previous owner had replaced it. Read codes. Only weird one was complaining about non functional EGR. Strange as this truck is federal emissions and no EGR on it, no place to put one. There is a round flat raised place in drivers manifold casting that I assume is where they drill and thread hole for the EGR tube, but it was never drilled. Anyway around June transmission blows, no huge surprise. I actually liked way the truck handled so kinda wanted to fix it. I got this idea I wanted a heavier duty tranny instead of the super light duty they put in it at factory. Way its geared, I dont really need overdrive anyway. Spent time, off an on, adapting a SM420 I had setting around out of an early 60s Chevy pickup. Its definitely hard to kill one of those. So thats done, but got to thinking about drivability quirks and recently pulled the ECM. Ran the sticker code on google and thing is out of a 1994 Explorer with MT and EGR. Ok, that explains the EGR fault code. I am guessing besides that it isnt reading some of sensors correctly. Reading online, seems using ECM for EGR truck not good for truck without EGR. Some stuff besides just throwing a code. No sign of a cheap federal emissions ECM for a Ranger without EGR. Manual tranny 4.0L seem kinda rare. They want half what I paid for the truck at the parts stores for rebuilt one and I am not absolutely sure what exact ECM came in the thing from factory. So is there any problem using ECM for an automatic other than it throwing a code cause it doesnt detect an automatic? I dont have emissions inspection so for now such a code is meaningless legally. How about a 1993 federal emissiosn Explorer ECM. Or 1993 or 1994 ECM from an Aerostar? I even ran across a thread on this topic somewhere, some guy said he was running his 4.0L Ranger with a 3.0L ECM. Well, both OHV 6cyl engines, I can see where that would possibly work if right wires from sensors went to the right pins on the ECM??? Those are very easy to find for manual transmission and no EGR and pretty cheap.