Ok. So I did some searching on here. I have noticed that sometimes people have poorly running cars or rough running cars due to air in the coolant system. I have recently changed my thermostat, so I thought I would burp the system to see what would happen.

The car still doesn't run right, but it is better. What else can you guys tell me about this? I made sure the coolant level was full, and ran the car with the cap off until it was warmed up. It still would bubble a bit. It didn't really quit. Now the car runs smooth when you go to higher RPMs. It will Idle at 1000-900. But its just a little rough.

If I go up to 3000 rpms or so, and hold my foot steady on the gas, the rpms will drop off by about 500, then if I let my foot off the gas, it will drop the rpms down to 2-300, or kill the car.

Do you think I need to burp the system more? It's the only thing that has seemed to make a difference, and I'm pretty sure the rest of the car is working right.

Also, Air bubbles in the coolant can move around. That would explain the instant problem, instead of coming on gradually. However the car ran fine after initally fixing the thermostat.

Any Ideas?

Edit: I took the car for a spin. It runs better. However, when I press in the clutch while coasting, the car will drop down to idle, and keep running. Then I can stop and it will stay running.

But If I press in the clutch, step on the break and come to a stop quickly, like at a light or stop sign, and let the rpms drop freely, the car will drop to 100-200 rmps. (I do mean 100) or just die. I haven't checked the speed sensor. Where is it and what does it do? I was pretty sure it just controlled the speedo.