89 Sunbird runs poorly when engines warms up

My 89 sunbird has been a true hassle. I have been able to fix every problem with this car until now. When the car runs for a while and the engine heats up, it begins to run very poorly and is very sluggish. does anyone have any ideas on why this is happening?

could be out of timing off or the coil getting hot or pickup coil in distibuter? whend did it start doing it? i had same car and the thermo is in radiator cap it could be upside down also. mine was when i bought it for my daughter you got the 2.5 right? you may want to check timing or put new belt on it and see if water pump is leaking you should have a sticker under hood to see what the timing suppose to be set at and how many mls you got on this car my daughter had 275000 mls on it when i sold it those are good motors.?.....good luck......

[quote=Scrapper;5973038]could be out of timing off or the coil getting hot or pickup coil in distibuter? whend did it start doing it? i had same car and the thermo is in radiator cap it could be upside down also. mine was when i bought it for my daughter you got the 2.5 right? you may want to check timing or put new belt on it and see if water pump is leaking you should have a sticker under hood to see what the timing suppose to be set at and how many mls you got on this car my daughter had 275000 mls on it when i sold it those are good motors.?

one more thing you might want to check your cat see if it's plugged and whens the last time you tuned it up?