I got home tonight with the chevelle and parked it in the garage and as soon as i got out the radiator puked. The temp was only at 190. Why would it have done that with the motor being so cool?

My MOPAR did that to me acouple of months ago. One isolated incident. I think that the radiator cap was not sealing good at the outer rubber gasket. The S***T radiator cap's gasket is just barely great enough in diameter to cover the diameter of the filler neck, and it was apparently not centered and allowed a leak. Got me a new AC Delco cap.

My $0.02

If you car doesn't have a coolant reservior, it was probably too full, there is a line about 1 1/2 inches down that it should be filled to and any more will cause it to puke.

I changed coolant a few weeks back but have driven alot lately with no problems.

I took it out again last night and it did it again when i got home. Temp got to about 200 cause i had the ac on. Could there be a problem with the cap?

Yes, but...

If you overfill the system, the excess gets vented when it comes up to operating temp. A non-reservoir system coolant level should be an inch to an inch and one-half below the brim when cold. If you fill it to the brim it will simply vent out when hot. It gets hotter for a while after you shutdown the engine.

See my post above about radiator caps. You can have yours tested or just get a new AC Delco cap for you system.

My $0.02