I had this same problem and It was my fuel filter. Engine surges because there is not enough fuel. Check it.
i does not have a control i need to replaced it
Could be spark in the motor, or the distributor and rotor need to be replaced.
shorted a wire? knocked a wire loose?
The IAC (Idle air control) valve is bad and needs to be replaced. Its about $200 parts and labor.
I also have a 2000 Venture same problem. Solution was tire balance weights fell off. They were replaced and problem resolved but....the tires were worn irregularly on the inside and I had them replaced.
The most likely reason that the heater control won't change the air flow is that the cable that moves the diverter valve has broken and will need to be replaced.
You shouldn't be driving it at all until those are repaired.
Check the ignition control module.
Possibilities: Cooling fan not working. Low on coolant. Clogged radiator, radiator hose or block.
your control module is bad
chevy cobalt
anytime of the day,with little or no changes.