I was getting a code for bad EGR or bad wire conection I replaced my EGR and then found the fuseable link for the ECM mem was burnt I repaired it and cleared my code 42 out. I still have a problem with the car missing up till around 2500 RPM this is how the car was when I bought it and somtimes it idles great somtimes it lopes. when I disconect the EST to set the timming it does not seem to change anything and I had to set the timming with a vacum gauge to get the most vacume but the timming mark is WAY advanced its off the timming tab compleatly the only other thing I havent tryed yet it put a belt back on the air pump (it is missing ) the air pump can be turned. I have a 85 Trans Am with 5.0 TPI do I have to have a 85 ECM or can I put another year ECM in it .

 

Take a look at the tech article. https://www.thirdgen.org/newdesign/t...erchange.shtml