Hello everyone. This is my first post on this website. I have a '94 GMC Sierra 2500 4x4 w/454 TBI and I only run premium gasoline with no ethanol and have notNew parts replaced beginning of may include (A/C Delco platinum spark plugs, A/C Delco high temp plug wires, A/C Delco coil, alternator, distributor cap, MAP sensor, 2 platinum batteries @780 cold cranking amps, all positive and negative cables for batteries and alternator upgraded to high output, radiator and all hoses, thermostat, k&N air filter, wifi/android app battery monitor, entire heat/A/C system, high end inline fuel filter, complete fuel pump/filter kit)
I have some wrench time in my resume but am still learning...this is my 74th vehicle since my first car in 1995. I've had foriegn and domestic cars, trucks, suv's and vans that have all had a problem or 4. Ive always been interested in performance upgrades and of course saving money. I have never had to put one in the shop...yet.
THAT BEING SAID....

ISSUE #1 ---- At cold start-up (regardless of seasonal temperatures) the engine fires immediately but will not continue to run unless I press the pedal before it dies to roughly 1800 rpm until the engine temperature reaches 120°-130° and then it idles at a mostly steady (according to the tach) 850-900 rpm but sounds like it has an RV cam....as soon as I press the brake pedal to put it into reverse or drive it stalls out and dies unless I press the gas pedal quickly....and it sputters and hesitates until I find the perfect place on the throttle (too much pedal and it loses power/stalls)...at stop signs/lights i have to put it in "N" to keep it running.

ISSUE #2--- after 5 minutes or so of idling rpms jump to 1,700-1,800 rpm. Tapping the gas pedal to try and get it to kick down does not work, truck has to be turned off and restarted.

Tomorrow, June 6th, i will replace the IDLE AIR CONTROLLER.
I will also use starting fluid to check for air leaks at all intake related areas.
All sensor plugs and wires are clean, undamaged and securely connected. Vacuum lines are securely attached and have no holes or cracks and have no flow restrictions due to buildup or blockage.
I'll check for replies frequently and I will post the results of the IAC replacement tomorrow night. If you are reading this then I really appreciate the time it took for you to read this lengthy post and any advise/comments you share...THANK YOU!!