Heat Sink Woes

My engine runs decently warm, hopefully that'll get fixed soon as $ permits. But anyhow. Brand new starter right, how subjectable is it to heat sink? Once my car gets to the temp it wants to be at and once I cut it off. I go to crank it up, it acts as if the starter (OEM Replacmtent) doesn't have enough power to turn the engine over. Once it cools off, cranks fine. Heat sink right? Any easy fixes? Thanks

fed up

Getting straight to the point. I've changed these parts to cure this problem with no luck. TPS (.97), EGR, EGR Valve, TFI Module, Plugs wires, Cap, rotor and button, IAC, batt cables (batt in hatch of car), starter, starter solenoid, coolant temp sensor, PIP and I believe thats it. Still, once the car warms up and I shut it off, it refuses to crank back up. It acts as if the starter isnt getting enough power to crank over the engine. I thought heat sink, but its a brand new starter. Heat sink still? O2 Sensors? I havent replaced those yet. Maybe? Maybe not? Thanks for the input.