IWhat else couldcause my van to overheat

I test drove the van without the thermos that and it overheated right away came back and added more water to radiator and test drove again and van ran good temp hardly went up, so I put thermostat back in and filled radiator with antifreeze and test drove and is still overheating.. So I'm guessing it could be the water pump??

I would think you need to get a better brand or better grade of thermostat. Yours is apparently not working right. Must not be opening enough.

I replaced the thermostat and water pump but still doing the same man do u think a coolant temperature sensor could play a factor in this

Can you read your last post. No thermostat runs cool, and good water flow. Thermostat in and overheats, restricted flow man. Usually a DIY'ers buy the cheapest part they can get, thinking they all work the same, and that's not true. I will give you some advice from the over 30 years of doing this day in and day out, so try it or don't. No sweat to me.