2001 overheating/no heat

Hi have a good problem for someone to solve.

I have a 2001 impala with 320k's 3.4L. The problem I'm haveing is the guage reads hot and light comes on, however the the cars not even warmed up yet. Also when car is warmed up the guage bounces around from normal temp (half guage or so) to hot to cold. When at normal temp on guage the car blows hot air, when its under a third guage it blows cold air. Car only does this every other day and only in the mornings. Once on highway for 20 minutes car temp runs normal and good all day. However now that it is colder -20C it is doing it more often.

Things that were done to car where 3 diff thermostats, coolant chked, grounds on car where chked.

The head and intake gasket where changed last Jan. with felpro gaskets, so that shouldn't be the problem??

So any ideas would be appreciated.

Thanks in advance Curtis.

did u look at the sensor that sends the signal of the temp to the pcm (I am not talking about the thermostat that opens and closes rather the actual sensor that temp sensor). Regards

Yep replaced that too.

I had the same prob on my 03 impala,come to find out i had a small leak in one of my hoses.I bought some prestone product for the radiator and it fixed the problem.

have you backflushed it

check the levels, and have you changed your intake gasket?