I've been doing some work on this truck and got it mostly figured out I think.

So far i have done new fuel pumps, rebuilt fuel injectors running at 38-39psi, new spark plugs, new egr valve, new TFI control module(fixed the bigger issue of dying). IAC is new, fuel pressure regulator new, PCV new with plastic grommet.

The final issue I'm having is the truck sputters (or maybe backfires not audible like out of the tailpipe, but maybe in the passenger exhaust manifold?? or air box area, a HUGE guess, I'm having trouble figuring out of its a backfire or the truck getting too much air) when I take off. It idles smooth, although a little high 900rpms, it pulls hills fine, it drives down the road smooth. It has high vacuum, but I had a shop do a smoke test and I have tried finding a vacuum leak with no luck, I'm told it could be the MAP sensor at this point. When the truck is warm and restarts the idle shoots up to 1500-2000 and then starts coming down to normal within 10seconds.

I was researching on my own and thinking maybe the EGR solenoid is bad, it definitely buzzes for about 15-30 seconds after the truck shuts off.

I was also told that with all of the new parts and fixes that the timing could need adjusted. I'm extremely hesitant to mess with timing on my own.

Any comments, thoughts or suggestions would be greatly appreciated. Definitely loving this truck even with all the TLC it needs. This is the last issue we're having unless this reveals something hidden/new.

 

Engine should REV and then drop down each time its started, thats normal

Easy test for air/vacuum leak
After engine is warmed up and idling, unplug 2 wire connector on IAC Valve
Idle should drop to 500-600rmp, barely running or engine may even stall, either is GOOD it means no air leaks
If RPMs do not drop then there is an air/vacuum leak

But you need to set timing as well since idle is also effected by spark timing
You need to get a timing light, ask around, older people have them sitting in their garages, lol, garage sales often have them, $5
If you have one then test timing after engine is warm and idling
Should see about 18-22deg BTDC
If higher then you will need to adjust it
Shut off engine
Locate the SPOUT Connector near distributor on the TFI wiring harness, looks like this: https://www.allfordmustangs.com/atta...ion-jpg.66251/
2 wire plugin with a black or grey plastic insert, pull out the insert
This disconnects the computer's "vacuum advance", Load advance used instead of vacuum advance but same thing
Restart engine
10-12deg BTDC is what you want to see, most prefer 12deg BTDC, adjust distributor to set it, but not done yet

You will also need to get the idle down to about 750rpms with IAC Valve connected, or 600rpms with IAC Valve disconnected, to do final spark timing

The hesitation and "backfires" are usually caused by spark timing and/or air/vacuum leaks

 

After doing the air/vacuum leak test you suggested the RPMs only dropped by about 100 and ran fine. So there must be a leak. After some tinkering around I noticed that if I completely block the intake tube with my hand the truck still runs at regular idle, 900rpms for now. I thought it would have died right away, but it ran just fine. What I did hear when i did that was a massive air leak around the intake. My first thought was that the IAC may compensate for the intake blockage, but I'm guessing I'm wrong about that. My second thought was that the intake manifold itself is leaking, maybe the gasket. Either way, I only hear it when I close off the intake tubing, not at normal idle or when I hit the accelerator.

I did a voltage test on the MAP sensor the results were 5 volts in and 2.4 out, which I thought was bad, but after doing some reading for Ford MAP you don't test voltage. Is that good or bad? Last night the fuel pressure regulator started spraying fuel everywhere so I'm checking to see if the o-ring is bad then replacing that or the regulator. Last night the fuel pressure regulator started spraying fuel everywhere so I'm replacing that as soon as the part comes.

 

Engine should stall if you cover the intake(throttle body) opening, IAC gets it air thru there as well, so it would be blocked
Yes, bigger vacuum leak

Yes, MAP sends computer a frequency not a voltage, some volt meter have that setting