1997 weird problem

[herefordman]

My '97 305 Vortec has kind of a weird problem, when it first starts off in the morning I watch the temperature gauge and it swings all the way over into the red before coming back and eventually settling out normal after a few swings, I've replaced the water pump because of a leak, and it also has a new thermostat and still does the same thing.
The heater is still blowing cold all the time this is happening, and warms up after it stops swinging (probably fifteen minutes or so)
Also and I'm not sure if these two problems are related or not, but at highway speed (not under load) when its coasting along it feels as though its stumbling or misfiring, it gets better after driving for about and hour but it is still there.
Anybody out there have any ideas ?? Help ??

[madmalibu]

If the gauge is swinging like that it is probably your sending unit which should be on the side of your block or on the intake somewhere. It's a cheap and easy fix. Also if that is telling the computer that your engine is cold when it's really not it might be running rich which could cause your stumbling problem.