I flushed the coolant on my 94' 4.0. Now the heat blows very very luke warm. I replaced the thermastat with no luck. It is heating up like normal. The radiator is new. Could it be a bad cap. I backed it down a hill thinking it would get rid of any air pockets. Any ideas??/

There are two ideas that come to mind:
1. There are air pockets (these work out of the system by periodically topping off the coolant, and be sure the reserve tank is at least 1/2 full).

2. The thermostat is the wrong size/type. I don't recall off hand what temperature thermostat is needed, but if there's one that has a higher temperature rating it will take longer before the thermostat opens up and lets the heat into the heater core.

ANY OTHER IDEAS??? Perhaps someone can add to the list of things to check.