When i first start my 91 camaro it runs good then as it starts getting warmer it stuuters and eventually shuts off. I have found that the ecm has been replaced i pulled the codes and i get 15 21 and 23 temp sensor has also been replaced i have found if i unplug my tps it wont stutter or die but does idle a little higher i dont want to run out and buy a tps if that wont fix it anyone have any ideas im lost

 

DTC - 15 Engine coolant temp sensor error (low temp indicated)
DTC - 21 Throttle Position sensor error (signal high)
DTC - 23 Intake air temp sensor error (low temp indicated)

When unplugging the tps it will run in limp mode which is just the computer guessing whats happening and with the other two sensors it doesent know how warm the engine is. first i would chase out the tps circut wires and make sure they are good (im betting this is a part of the problem) second check wiring on all sensors maybe a common ground broke off the harness lastly replace tps and see what it does

 

Both DTC21 and DTC23 likely mean a missing ground. The TPS and IAT (MAT) sensors share the same ground return wire to the ECM. Check the black wires on those two sensor connectors and trace them back to a splice somewhere. From there it goes to the ECM connector C1 pin B5.

The ECT might be defective or have a loose ground connection, once again at the black wire. That wire is separate from the other two sensors and goes to the ECM connector C1 pin B6. If you also see DTC33 for the MAP, that would indicate a bad/missing ground return wire there also.