My 97 monte carlo z34 engine heat gauge shows it is always hot while and after i drive it the gauge goes up and down also i know i have to replace valve caps it smokey and burns gas could that be why its getting hot and how do i relace the valve caps

https://www.2carpros.com/questions/2003-chevrolet-monte-carlo-coolant-temp-sensor-location

No Start Diagnostic Basics EricTheCarGuy

You don't have to pull it to replace the TCC. Remove the pan and you can access the TCC solenoid.

Make sure fans are working properly, if ok, replace tstat and seal and recheck.

have a coolant pressure test done. Have the radiator cores checked for blockage. Sometimes when an engine has sat for a period of time, rust and scale form in the water jackets of the engine. ON running ,this breaks away and blocks the cores of the radiator Other times the old motor tolerates a partially blocked radiator when a relative new motor needs all the cores free to maintain the temperature.

Very common Transmission code - solution # 1 check to be sure Fluid is full . If not trans code sent plus will turn on check engine light or service engine soon . # 2 be sure condition of fluid is Good / Not worn out . Fluid must be Red / Reddish in color Cold and When hot- warm still have red / even lighter than when cold .# 3 if a higher than 50,000 mile car used in heavy rush hour traffic during hot weather then change fluid to give it fresh oil / Trans will fight heat better and save you a $$ 2000 repair bill . # 4 most important of all you can save a Trans by adding Lucas Trans treatment it is $ 20 some places but well worth $$ to extend life of vehicle if one in need of saving $$ .This can even be added to existing fluid if color is still reddish .

check radiator fluid level it take hot radiator fluid to pass through the heater core to produce the heat in your car VIA the fan. also check or replace your thermostat it could be bad and stuck in an open position thus radiator fluid not getting hot, no hot fluid no hot air
the other problem sounds like a duct hose under you dash has come loose locate and reattach.

Hi;
If your engine cools down when moving fast, you either have a problem with your water pump or your electric fans that cool off your radiator and a/c condenser. This is controlled by a temperature switch, but these fans should kick on instantly when A/C is selected.

I had a similar problem on a 3.4 Lumina Z34. It was a leaking intake gasket. Be careful with the plastic vaccumn lines as they will get brittle.

it does sound like a bad crank sensor