01 Malibu continues to overheat

I have an 01 mailibu that keeps overheating. I have replaced the water pump (twice) and had the thermostat replaced. The water pump and thermostat were replaced about a month ago. Last night while driving, i noticed the temp getting higher, so I turned on the heat, and instead of hot air, it was ice cold.
I am about at my wit’s end. Any suggestions on what it could be?

Sounds like it isn’t recirculating properly. Let’s start at the basics:

Have you ‘burped’ the coolant?
This is done by parking the can on a slight incline or ramp, taking the radiator cap off, starting the engine and goosing it a bit. You’ll notice air bubbles come out of the filler neck. When you do, add more coolant and do it some more until you don’t see any more burping.
Your car may have a bleeder valve on top of the engine that basically does the same thing.

Under most circumstances, when you replace the coolant (as clearly you’ve done) is is best to take the top radiator hose off, put a funnel into it and fill the coolant into the engine first. Very quickly put the hose back on the radiator and then fill the radiator.
Some cars are very stubborn in not wanting the engine to be filled up from just the radiator.

I am not positive but I think the Malibu has a burp valve on top of the thermostat housing. 7mm wrench to open it and allow some air to escape. It is also possible the radiator cap is failing to pull fluid back from the overflow tank during cool down because of a sticking mechanism inside. This is pretty common to GM and Dexcool degradation.