I bought a 1993 Gmc Vandura Starcraft conversion van with a 5.7 and a 4l60e trans starting from the begining. I bought it out of colorado (no rust) the trans was malfunctioning it would only shift manually and when warmed up it would start off in 3rd gear. I ourchased a reman trans and installed it and when its cold it shifts fine when the engine gets to operating temp in OD it will start off in 3rd gear and will shift up from there if you pull it down to low it will start out in 2nd that is problem one. The van now is giving me another headace it started today while I was trying to figure out the trans problem it started running terrible. I ran a scan and it said it had a bad idle air control so i replaced it now it will idle but still ran bad so I checked the injectors and the left one is firing and the right is not at all switched the plugs and then the right would fire and not the left. So i have a problem with the wiring or something have power to it and had a new ecm so tried it and the old one did not change anything. I am at my wits end with this thing anyone that can help would be my hero I dont know what else to do Thanks Keith

 

a. you cant start off in 3 gear without stalling. How do you know what gear you are in? are you counting the upshifts based on speed? YOu can start off in 2nd gear(in 2nd-and stay in 2nd) but not in L. In L it is mechanically prohibited from upshifting past 2nd and always starts off in 1st.

b. In OD, the only upshift is to 4th gear(at highway speeds-45mph and above). OD and D are the same until that point.

There is alot here but let me ask: Did you replace this with a perfect match 4L60 for a truck or a car? Same transmission but 2 different wiring harnesses. I think your problem is electrical. Bad ground on the transmission or interface fault with the valve body. Remove the trans harness and check for missing or bent pins. Check for rust or frayed wires in the connection. Maybe an disconnected ground wire.