i have a 92 lumina 3.1. after car sits for several hours (overnight) its hard to start. after it starts car runs fine and starts right up. changed fuel filter left it sit, same as before. what else should i look for? plugs & air filter are ok. it seems to be fuel related. does the fuel press regulater keep fuel press in line and keep fuel from draining back into tank? any pointers of what to check? thanx