I have a 94 mustang and it is overheating...i had to put 2 qrts of oil...when i start it i shakes a lot but then it goes away once it is on for a while. the check engine light is on... i do not know what it is. can it be the thermostat?
Do you have any external oil leaks? If not, your engine may be burning oil either because of worn valve stem oil seals, worn valve guides, or worn piston rings. Pull the plugs and see if they're fouled up with oil.
A thermostat that's stuck closed will cause the engine to overheat very quickly about 2-3 minutes after a cold start. When does your engine overheat and how hot does it run?