454 TBI surging/loping

[Tiger Joe]

I made a thread a few months back about my TBI surging, I thought I had fixed it however its back and appears worse.

so backstory- truck was getting horrible MPG. unknown history so I decided to rebuild throttle body. in process found fuel lines rusted so replaced those.

when I installed rebuilt throttle body and did IAC relearn, I was having issues. turned out to be a torn o ring but I had already bought a new one so swapped it.

everything seemed ok, but every once in awhile truck would lope- like it had a cam in it. drives great, only does this at idle or creeping in low (truck is NV4500).

so here is everything that has been done to the truck:

previous mods:
new ditsrubutor and coil
adjustable FPR (set to about 12 PSI)
TB spacer and better air cleaner

in past 3 months
rebuilt TB with new injectors
new fuel lines
new IAC
new Throttle Position Sensor
new MAP Sensor
new O2 sensor (heated upgrade)
new coolant sensor

I dug out my old Chinese tech 2 and figured out how to read the data on the truck. I attempted to set the IAC count down, and it would be good, but when I start truck up it goes right back up. so for example I try to set to 15. its good, restart and its up to 30.

I tried doing the IAC reset jumping terminals- when I disconnect IAC the truck lopes VERY bad and barely runs- it was not doing that 3 months ago. I also noticed if Im sitting in the garage and I raise the rpm slowly, it will climb to about 2400 or so, and then randomly drop to 17-1800, and then rise again, and just do that over and over.

ive checked timing, its good steady not jumping. I checked for vacuum leaks with propane, nothing. I checked EGR and PCV, both seem good to me.

at this point im lost. I dont know where to turn next. every time I think it's one thing and I change it, it runs good for a few miles, then random lope again.

when this first started back in march- it was NOT loping when I tried to do IACA relearn, so to me it seems to be getting worse.

I have a couple screen shots I took of my tech2 screen today when I had IAC set good and it was idling nice. then I shut off restart and it lopes. maybe someone can tell me if anything looks off?