malibu heater problem

i changed the thermostat on my 99 malibu and drove it for a while and it done good for a while but then it started overheating again and the heater will not heat now does any body know what my problem might be

Need to do a coolant bleed procedure, because of the air pockets in your system.

we bled the air out and it still overheated but i am going to do it again

we bled the air out and it still overheated but i am going to do it again

get an infared temp gun and check it, when sitting in traffic my gauge shows a couple hash marks higher, but when I temp gunned it it is only about 10* more than it usually is, so long story short very little change over the norm and my gauge interprets it as a big change, this IS NOT normal, I AM NOT saying this IS your problem, just something to check. If you really are overheating by all means shut it down when the gauge says so...