Hello! I have been doing searches on this and other sites to try and figure my issue out, but I can’t quite seem to find any posts that address my particular issue. So here it is.... a little backstory is required....

I have a ‘93 22RE pickup truck. It ran like a champ, rock solid temperature under all running conditions and good heat in the cab. Then during this winter something happened on a VERY cold morning that caused the engine to overheat and started dropping coolant. Was able to keep it full and cool and get it home. Upon inspection it looked like the L-shaped tube for the throttle body bypass had given way. Due to an issue with how it broke a new part had to be machined by my local shop. I also replaced the T-stat (88-degree one). All was fixed and should have been good. By the way, the radiator is also reasonably new (less than a year). Replaced the t-stat again and backflushed whole system.

Unfortunately since that fix the temp fluctuates - runs at what I consider “normal” temp while idling after running for a while but then drops down to running cold when the car starts moving again. Also, there is NO HEAT in the cabin. I have done a backflush of the whole cooling system and backflushed the heater core twice. It seems the lines running to the heater core never get hot. Also when I last changed oil (couple weeks back) I noticed what might have been a few drops coming from the water pump, but I wasn’t sure.

Haven’t been able to find any threads that discuss this particular set of problems. Any idea of where to look next is greatly appreciated. Thanks!