Heating Problem

About 2 years ago I replaced the factory 180 thermostat in my wifes 2000 cavalier with a 180 Valucraft from Autozone. I also changed the coolant and bleed the system for air. Ever since that the car doesn't get hot enough and the temp gauge doesn't run at normal temp on cooler days below 50 when driving but if its just sitting idling for awhile it will. On days from 50 or above it runs at normal temp idling and driving. A month ago I changed the thermostat again thinking maybe the one I put in was just a bad thermostat. This time I got a 180 Duralast thermostat also from Autozone. I also changed the coolant and bleed the system once again. I'm still having problems with it not getting hot enough on cooler days. A co-worker of mine has a cavalier and the samething happen to him when he replaced his thermostat which he bought at Autozone also but he did the cardboard trick in front of the raditor and it helped get him heat. I'm starting to believe its the quailty of the thermostat and its opening to soon and it's not allowing the system to gain pressure to produce heat. I'm thinking of going to the dealership to get a OEM thermostat. Anyone out there have this problem or input or fixes on this? Any info is Appreciated

yes, i can speak from experience, autozone thermostats are complete shit, i think all generic auto parts store brand thermostats are shit, but i know autozones are, im sure this is your problem

I had the same problem with my 2.2, I think it was a 175 Duralast one from autozone, didn't make the car hot enough, the fan barely ever came on, if it did at all. Made me fail inspection too.

Thanks for the info. I wasn't sure but I kind of thought that might be the problem. Stopping at the Dealership tomorrow for OEM thermostat