03 silhouette overheating

I have replaced the thermastat & got a new radiator cap. Done a do it yourself flushing system. With still these problems. Just replaced water pump same issue. Over heats & at idle with no heat while hitting gas temp gauge drops & I have heat. Done the 2 bleeders on them and its on & off. Sometimes I have a steady flow other times it spits out alot of air. I have let it run till had a full stream shut it off let it cool down & still nothing.

You need to do a system leak check-- your engine is known for intake manifold leaks and head gasket leaks.....

A cheap do it yourself check is to put a plastic bread bag over the radiator lip- secure with rubber band--- start engine, if bag blows up, you are getting exhaust gases in your cooling system-- means bad heads gasket, or cracked head....

I assume you have looked for external leaks.....

And whenever you open up the cooling system, you MUST properly bleed the system.......if you don't you then have an air pocket, which can cause overheating.....a great tool to use on any engine for air removal, is a Lisle Funnel setup....

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTnga_YBStOaxTu2ZcvH11ON-5Y6mC6TnIor9KQ572wLRv0vfbV

This virtually eliminates all air in the system.....

But as mentioned, this engine is known for lower intake gasket, and also head gaskets, particularly, at cyl #1(passenger side rear).....

If you don't have a pressure tester, you can borrow one from places like AutoZone(basically you buy it, use it, and then return it and get your money back....that's how their loaner program works)......get the vehicle up to normal operating temp.......then let it cool down enough so that you can safely remove the radiator cap......now pressurize the system overnight.....then next day, remove all spark plugs and disable fuel and spark(remove the two wire connector to the ICM on the passenger side).....now have someone crank the vehicle, while you watch the spark plug holes....if coolant comes out during cranking, then you have a head gasket leak out of that cylinder....the most common one is cyl #1(passenger side rear)....