I have an 87 chevy R-10. 350-350 combo. Engine has tbi on it. I have recently been experiencing some trouble with the engine running properly. It runs fine when the motor is cold but when the motor gets hot it wont want to idle in gear. It will slow down and want to die unless i brake torque it(which isnt the safest thing to do). I have replaced the idle air motor and the fuel filter is fairly new. I have also tested the throttle position sensor and it tests good and I have tested for vacuum and all is well there. Any idea's would be greatly appreciated.