Jim Price

anyone with experience? I have this model that, because of horrible rust had a rcall on the cooling system in 1997. They also added a hose bypassing the inlet side of the heater. I had this done in 97 and everything worked ok until a few weeks ago when the heater stopped working. I took it to an independent mechanic who first determined the blend door was operational, then decided the thermostat needed replacement. Heater still did not work, so the water pump was replaced. Still did not work. I checked heater core inlet, it was hot - outlet only tepid. I drove it three weeks without a heater at all, then suddenly it began to work, although when at idle, it works poorly. Mechanic had flushed heater core out on first visit. Anyone have an idea? I wonder if there was an air block or if the core was plugged and is moving out.