The temp gauge on my yukon keeps going up to about 200 and then back down to normal. I replaced the thermostat thinking it was sticking, and the sensor under the thermostat was broke so I replaced it, neither worked. I then found that the water pump was leaking and replaced that, and I'm still having the same problem. Anybody have any advice as to what I should do next?

Sounds like you have air in the system. Pull the truck up on some ramps and take the radiator cap loose. Let it run for awhile and keep checkin the water.

Sounds similar to the problems I started having with my '96 Tahoe. Everything boiled down to the Dexcool. It had started to turn into a kinda "sandy-goo". It had even plugged up the heater core completely! I ended up replacing the thermostat, water pump, and I even ended up having to replace the intake manifold gasket. After a complete system flush, I switched back to good old green anti freeze. No more problems.

Good Luck!

T

the Vortec motors seem prone to eating the intake gaskets anyhow. I would check to see if yours may be leaking. Both of my Tahoes have needed them.