I recently purchased a 1985 -2.5l standard
It is having major overheating problems.
After driving for about 1/2 hour the exhaust manifold gets red hot. It has already melted the throttle linkage and the covering of the oxygen sensor. Can someone suggest an answer?

It sounds like you have a major vacuum leak or timing issues, but most likely a vacuum leak. Check all your vacuum hoses for cracks, disconnections, or missing hoses.

Also check for a blocked Catalytic convertor