we changed the thermostat and that did no good. what else could be the problem.

It could be a blown head gasket or your radiator needs flushed or replaced,

It could be the harness l think. it better to get to a mechanic u trust because this job could run you up to 3200.00

There r several things that can cause this problem. l would have started at the thermostat also. You may want to check for water in oil or oil in water due to cracked head. l would also check to see if u have coolant running throw the system by trying to see movment in the tank after the car heats up. Impellers on water pumps can fail without being seen (leaking ect.) . If u know u have cerculation & the radiator is not stopped up u could also have a timing chain problem, If the chain is streched to much it will cause this problem due to incorrect valve to piston timing. Hope this helps.

l think it can be as simple as having some air in the coolant system! or maybe you rad it`s self has gone bad!i say check for air in the system 1st!

If it is a 93 & has the original radiator in it, l would look there first. If the vehicle is ran with tap water in it the tubes in the radiator could be plugged, preventing coolant from flowing freely. What is the condition of the radiator? Are all of the fins smashed or r they still straight? If u replace the radiator, look into a radiator filter such as a ''tefba'' which will prevent this from happening in the future. Over heating can be many things but if the radiator is 14 years old then it will not hurt to put a new one in. Run DISTILLED water mixed with coolant when u change the coolant. Make sure there is not any coolant in ur oil first.