my 1990 firebird with tbi is hard to start in cold weather, it starts up just great when it's warm, but the colder it gets, the harder it starts. what happens is while it's cranking, it fires up and you think it's going to start, but as soon as you turn the key back to the run position it either hessitates, and catches itself and continues running, or if it's real cold, it dies all together, I've replaced a lot of parts to try to fix it and the best i can figure, when the key goes back to run the ecm hessitates, trying to figure out where to put the timing. it's almost as if the ecm is senile and can't make split decissions when its cold