Ok so I swapped my original 420a from my 95 eclipse RS because piston #1 was cracked.. the engine I bought was from a 95 avenger, that I saw run prior to purchasing the engine... swap went fine, only issue was the crank position sensor that didn't have the same connnector for my engine harness, so I took the sensor from my blown engine and put it in the new one... I also put my intake plenium because it was in better condition then the other ( cleaner) and torqued everything down to spec using new gaskets.... started the engine up, and it holds around 4000 - 4200 RPM... checked and ajusted the throttle cable, it was fine.. all vaccum lines arw hooked up fine... swaped TPS sensors, and IAC valve.... got same result after trying each part... even tried with the other ECU, and still the same issue... now I didn't have my OBD sacanner with me but besides a misfire code, everything seems in order. So a little help here would be appreciated!

You've never seen a "CRANKWALK" ???