no power when cold

I have a 1985 olds cutlass cierra. It has a number of problems but now the latest is that when its cold or hasnt been run for a day even in warm weather it starts idles fast, then when i go to drive it it gos about 10 feet then it sputters out unless I put it into neutral and really floor it to keep it idling, again i go to put it into drive when i think it should be warmed up but it will do this again, in drive the idle is irregular so I need to floor it to get the pwer i need to get up to speed otherwise it will stall. It does this for about 15mins before it is really warm then it runs a little better and idles slow but it needs half as much gas pedal to make it go..when it stalled at the beginning once there was alot of smoke coming from under neath so i looked and i saw that the exhaust system i think the catylic converter was bright orange meaning it was extremely hot.. It seems that it satrting doing this when i bought some stop oil leak liquid that i put into the oil case or i put some gas carb cleaner thatput into the gastank...It could be coincidence but Im not sure.
I believe my car is on its way to the junkyard unless i can figure this problem out...

Any help is appreciated,
Kevin