22RE Studdering/Hesitation/Backfire HELP please!

[eightnine]

hey everyone i was hoping one of you more experienced guys could help me out with this problem iv been having with my truck, ill do my best to make it short. The truck seems to studder/ hesitate and backfire when i try to accelorate from a dead stop. It will keep on backfireing and studdering for about 15-40 seconds of driving and will eventually pick up and drive normally. Even if it stops after driving once i stop at a light or let it idle to low for any amount of time it begins to backfire again (The engine/truck also vibrates when it is idleing at a stop in DRIVE but not in NEUTRAL ???). Another thing is that this USUALLY only happens when it is a hot day, not so much when it is cold. Oh yeah and gas milage sucks really bad im spending like 20$ every 2-3 days of just driving to school and work (about 30 minutes of driving in total a day).

The Things that my mechanic and I have tried already:
-Put in a new timing chain set (chain, guides etc)
-Put in a new TPS or throttle positioning sensor
-Put in a new Mass air flow sensor box

After all of this the problem still persists although not as bad as before. I dont no what else it could be and these parts are really costing me a lot. The only other thing i can think of is the catalyic converter being clogged but i dunno how that is possible because it is only 5 months old (its a big turbo performance cat). Hopefully someone will have some ideas, thank you for reading

 

[imagemaker]

Man, Id love to know what you found out. Mine is doing something very similar!

 

[morganism]

Grab an extra piece of vac hose, start truck, attach vac hose to top of EGR valve top hat.

Put hose in mouth, and tap on side of EGR right below tophat, while sucking and releasing vac, try not to stall it out completely.

Listen to rocks fall down into oil pan.

Drive normally again