ok well I just bought a 94 eclipse 1.8l yesterday. and I was just cleaning up the engine bay and was checking the air filter. and cleaned off the battery because it had some corosion on it. now after I hooked everything back up the car started then instantly died. then after that it would start then after I would rev it up a bit or try to drive it the minute I left off the gas the car would die. I suspected a vacuum leak but after looking everything over nothing seems to be out of place no cracks in the boot or anything like that. so I disconected the battery because I heard it can reset the ecu. then hooked it back up the car ran fine and didnt die after letting off the gas. so I took it for a spin, while accelerating everything is fine then when I let off the gas the car starts to run really rough. but when I come to a stop the roughness drops down then it runs fine again. it only runs rough when I let off the gas while driving. thanks for any input or help anyone can offer me to figure out whats wrong. I am sure there is something I might be over looking or just dont know seeing I am new to this car.

is it an automatic or manual tranny?

ok I think I am correct in assuming that the 1.8 has a MAF sensor. If you checked the air filter make sure that you didnt accadentaly pull the connector off the MAF. This is a broblem that I had for about 10 miles till I poped the hood and saw my stupidity. It does happen and it will make the car run on the wrog mixture.

it is a manual trany, and I did disconect that connecter and totaly forgot to plug it in when I first started it but it imediatly died when I started it. then I realized it thats when I hooked it back up and disconected the battery waited a while then hooked it back up. so I have no Idea what the hell is going on.

when you unhooked the battery, you lost the adaptive idle memory.
to get it back to normal you're going to need to THOROUGHLY clean the throttle body.

hey thanks for the input everyone well it was running really good today. no problems what so ever it still runs rough at idle but I just figured it needed a tune up. me and my buddies every friday night hang out where we like the call the monster garage. its my buddys garage and he is a parts manager at a chevy dealer. and my other buddy is a mechanic. so we just tinker and fix stuff so I think this weekend we will do a tune up and clean out that throttle body. thanks for the help and I will let you guys know the outcome of the tune up.