Hello this is my first post so i apologize it is in the wrong place. I was given my truck around 10 yrs ago by my father and around 1 1/2 yr ago it started sputtering sporatically and i was thinking it was my smog pump due to the roar coming from what i think is the check valve. I replace the belt to bypass the pump and the truck started acting fine untill a few days ago. When sitting idol when i first crank it up it will sputter, or when i wake up later than ment to it will while driving also. When it gets up to temp it stops sputtering completely and drives wonderfully. Ive tried the tps and for giggles checked both temp sensors and they were both fine. Ive changed my fuel filter just in case and all to no good results. I have a 4.9 L6. Im pretty mechanically inclined ( commercial trailer, refeer mechanic ) but unfortunately i learn as i go. Any help would be greatly appreciated. I also changed the plugs, wires, dristributor cap, and button.

 

Have you checked for any DTC's?

If it's a speed density engine, I'd suspect the MAP sensor, if it's a mass airflow, I'd suspect the MAF sensor.

 

I thought it might have been the map sensor so i changed it and no results.

 

I have also changed all the vacuum hoses as well

 

smoke test? intake manifold sealed up tight?