at 200 degrees no heat, worked fine before, everything is hooked up as it was, what could be the problem

 

I have that same problem! except, the radiator I put in mine was different from the one I put in there! The factory had a hose coming out of it going into my heating core. I put a radiator out of a formula 350 in my TBI L03 305, and it was missing that! I had to buy 1' 1/2" of 5/8" heater hose from my heating core, where it used to mix into the radiator, and connected it straight to the "T" that connects the rest of the heater hoses! My heater dosn't work either! ????????????????????????????????

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89 Firebird LO3
Open element, MSD blastercoil, ACCELL cap and rotor, Moroso 8mm Blue Max wires, #2 Rapidfires, straight pipes, and keyless entry.

 

Check that you hooked the vacuum line up to the heater control valve. It could be overlooked and i believe that would stop your car from activating the heater core. Assuming you hooked everything up right nad the line is hooked up maybe you should replace that valve? i'm outa idea's

Matt

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89 Camaro IROC 5.7L 350"
ZZ4 Performance Cam, K&N Air Filters, 160 stat, Ported Plenium, Hypertech Airfoil, TB Coolant bypass, B&M Stage II Shiftkit

New engine on its way with a HOLLY instead of all this TPI crap.

 

Maybe your'e air bound in your heater circuit. With cold engine, remove radiator cap, start engine, turn on heater. Let run at idle until all air comes out of radiator neck. If you have air, it will be pushing coolant out the radiator neck as well. Once coolant stops overflowing radiator neck opening, refill radiator to top while engine is running. You should notice heat from your heater at this point. If not, air in your heater circuit was not your problem. Probably defective heater control valve (ie water valve) as others suggested.
FJK