Need more help and advice guys on my cursed 90 Mighty Max with a 2.4L.

As most of you read in other threads throughout the past year, I got this thing cheap, solid - but ran like crap. Had evidence of a coolant leak on #4, so I pulled the head to replace the head gasket.

Had the had cleaned and they found a crack between #3 and 4...so new Clearwater Head. Has the injectors ultrasonically cleaned. Cleaned out the entire intake of every bit of carbon, including all the corners to (hopefully prevent future buld-up. Cleaned out the EGR and bench tested it OK. New cooltant sensors, new O2 sensor, new throttle body (mechanic tested original one had leaks) new exhaust incl. new CAT and new exh manifold.... yet it STILL Ran rough - almost misfiring.... ran it like this for 10min and exhaust began to superheat. So bad in fact the space between cab and bed was too hot to touch and new muffler discolored slightly. Getting black smoke and black soot out tailpipe and was still getting 6mpg avg when I did drive it short distances. Basically running rich.... super rich. But it ran with a good idle rate.


Opended up ECU and had the blown capcitors replaced by AvPro, juat got it back today and installed it.

Now guess what... It actually runs good, no more steady black smoke and "misfire", old chunks of soot being blown out clean....but the thing is running at super high rpm cold.

No tach, but I'd guess it's at least 4 to 4500rpm. Had helper verify on startup the throttle cable is not moving at all and has no tension (slight slack). Slight tap of gas pedal adds another 500rpm or so. Dangerously high for a cold startup I think.

So...do I start looking at and idle speed motor, or idle speed postion sensor, throttle position sensor, etc even though the thing ran normal rpm before the ECU repair?

Or does anyone think AvPro screwed up my ECU?



Jim