95 grand am runs bad when warm

Hi all, I have a 95 DOHC Quad 4 grand am, 13,000 miles ago I rebuilt the motor, almost everything new. This car sits more then it gets driven because it isn't that reliable (seems like its always something going bad). A couple weeks ago on a hot summer day I drove it, noticed the temp was up near 200 degrees, went thru a drive thru and it jumped to 220 degrees, parked and ate my dinner (with the car off). When I went to leave the car ran fine, pulled up the light & had to wait for it to go thru it cycle, when I got the green the car started to miss, got me thru the intersection then died on me, so I pushed it to a parking lot, cranked and cranked but wouldn't fire. Since I had no where I had to be and had some tools I swapped out the Ignition Control Module - Coil packs - & coil housing with a spare one I happened to have in the trunk, since I knew my spare parts were good I was thinking this is my chance to see if its my ICM thats getting hot and making it shut down. Didn't work, but right after I got ahold of a buddy to get a ride it fired up (almost like the engine cooled down enough to fire). So when he showed up I had him follow me home, no problems.

The next day I decided to do some testing, fired the car up and let it idle to see how hot it would get. With the hood open it wouldn't get above 200 deg, closed the hood and it jumped to 220 without much of a problem, then at 230 the fan kicked on, took it down to 220 and shut off. Now atleast I know my fan works, seems kinda hot, but im guessing its right. Decided to take it for a spin while its warm, pulled out of the driveway and started missing real bad, let off the gas and it stayed running, when it smoothed out I hit the gas again and away we go like nothing is wrong. So a couple days later I thought i'd make sure I didn't have an obstruction in the overflow tube going from the water outlet on the head to the overflow tank (metal line that runs along the backside of the motor), it was clear.

Thinking it could be a thermostat, but I remember putting a dealer thermostat in when I rebuilt it 1.5 yrs ago 13,000 miles ago. I put a brand new full exhaust on it last year (exhaust manifold to exhaust tips), so its not a cat issue. I changed the fuel filter about a year ago. I've heard of this kinda thing happening when a fuel pump goes bad, but I don't understand why it only does it when the motor is hot. Oh I also replaced the water pump during the rebuild.

Anyone ever have this happen to your car? What fixed your car? Any ideas?

Hav you tested your Crank shaft postion sensor(s) ?

I hav seen them fail when they are bad and get hot.
As soon as they cool down, it fires up and drives, till it gets hot again.

It is possible that any thermostat can go bad or not work quite right, even from the dealer. I know its a pita to change/remove it in the 4cyl. Just a thought anyways.

Hope this helped,
let us know what you find out.