Running Hot.....Help

[84LX89GT]

Does your car get hotter when it's standing still, while it's moving or both?
The fact that you underdrove your water pump and also that a flex-fan reduces in efficiecy as you move (also when they get older i've heard they tend to "flatten out" earlier in the rpm range) could be the problem in itself.

about how many degrees temp do you think you're running? Does it keep getting hotter once it starts or does it top off at a certain temp?

Probably one of the most common fail items is a thermostat and they usually cost under $13. I bought a 180* for my GT and it works great. This is probably where i'd start. You may also want to pressure test your cooling system because if the system doesn't stay pressurized the boiling point of your cooling system goes down and it's ability to cool is diminished greatly because the coolant may start to boil causing air pockets.

Good luck, keep us posted, and get more detailed on what's happening.