I'm relatively new at this DIY vehicle maintenance, so I'm not sure as to what in the world is going on. Here's the problem (or should I say problems) that I am having. I have a 1990 Civic Dx that I bought from a friend. It started overheating so I tried to find out what the problem was. I noticed that there was a small crack at the top of the radiator where the antifreeze was spewing out of... sort of like a massive volcanic eruption. I managed to get that fixed but it is still overheating. It takes 5- 10 minutes for the vehicle to warm up, but when it does the hot and cold gauge blows it's top off.I start thinking maybe it's the thermostat. The top hose gets hot, but the lower hose remains cold. The next problem that I was running into was the fact that the engine seems not to be getting power. It drives along fine for a while, then all of a sudden when you press the gas pedal it doesn't want to go anywhere. It stumbles for a little bit then it picks up speed as if nothing were wrong, until you stop the car again. I thought it may be time for new spark plugs... I don't know... Someone please help...
Nala

Remove the spark plugs and perform a compression check on each cylinder. You need to verify that the head gasket, head, and valves have not been damaged from overheating. This is common on these older Hondas and could account for the loss of power. If everything is fine:

. Replace the thermostat.

. Replace the radiator--phosphate scale is likely blocking passages in the radiator:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post235973

. Refill with a 50/50 mixture of antifreeze and distilled water.

My gut is that the head is warped, the head gasket is blown, and the valves are damaged ($2,500). I hope I'm wrong.

Thank you. I really appreciate it.