I have a 2004 maxima. I’ve changed the radiator the thermostat and, the water pump. It’s still overheating. I notice when I rev it or, drive it hard the temp drops to normal/half way. Can someone please help me out with some suggestions.

Health of radiator cap? Tested? Replaced?
You likely still have air in the system. Re-check.

I haven’t replaced the cap or tested it. You think an after market one should be fine or, should I buy an OEM?

For this part, I imagine the difference in cost between aftermarket and OEM is marginal. I'd go with OEM to play it safe.

Burp the system. Make sure to turn the heat on max speed to open the heater core.

With the cap on or off

Cool thanks. I appreciate the feedback.

Raise the front of the car, attach a funnel to the radiator, fill with extra coolant, and run the engine up to temp. Revving the engine will help remove air bubbles.

if you don't have a spill free funnel check out OEMTOOLS 87009, Lisle 24680, or similar.

so just open the cap and place the funnel on the opening then let the car run with it open until it gets up in temp and rev it until I don’t see any more bubbles?

Off

If you can park on slight incline, with the radiator higher than the rest of the car, it can help burping the air out easier.

will a bad heater core cause the car to overheat as well because the cap looks to be in good condition and there’s no leakage on or around it I was thinking it could be either the heater core or the temp sensor the car runs mostly normal/half way but gets about 3/4 until I either rev it or drive it a little hard

If that is the original radiator cap, then get rid of it. The spring has gone through too many cycles to be of any value.

Just an update I removed the thermostat from the housing and the temp has been fine every since but of course it just takes a lot longer to heat up but better than 3/4 of the way or overheating 🤷🏽‍♂️

I have a 2008 that was doing the same, Replaced radiator fan assembly, problem solved.

I have a 2007 Max, and I was having the same problem: I replaced the temp sensor, radiator, water pump, - no success, still overheat while idling. Finally, replaced the radiator fan and problem resolved.

i got a 2 row vietnamese/china all aluminum radiator and a new thermostat and fan assembly, in the process of burping it. might have put the cap on too soon, never replaced the cap yet, the china cap that came with ther ad. is 1.3 bar, aka 17 PSI! the oem cap is 88kpa (12 PSA), i ought to get a new cap and finish burping

burping helped but, its pushing fluid out the top of my old cap, i don't think i'm going to run the Spawon cap that is 1.3 bar/17 PSI. factory caps is 88kpa, aka 12 PSI. i'd rather get a new 12 PSI cap. maybe 15 lb.