Pontiac Repair: 88 grand am cold start issues, quad 4, cold start

Question
whether it sits overnight or just a few hours , when cold, she starts fine, runs fine for a min or two then the idle drops and she vibes real bad and i have no power, floor it and she will steadily but slowly rev up, try to drive and its like trying to drive a semi with a 4 banger, she will drive but no power just a steady slow acceleration then about 20 min or so of that she will just instantly kick back over to full power and a smooth idle like nothing was wrong at all and i can drive her all day like that till she sits for a period of time or overnight again..

Answer
Hi Kevin:
What 4 cylinder engine is in this a quad 4 or a tech 4. It sounds like it's misfiring. it could be from a bad ignition coil or plug wires if it's a tech 4 if it's a quad 4 it could have a bad spark plug connetor between the coil housing an the plug. If it's a quad 4 it could have a bad coil housing. does it act up more if the ambinet conditions are humid more so then not? If so it would lean more towards an ignition system problem then a fuel injection issue. that is where I would start. good luck :)