another TBI problem

[Blue_71]

problem--
after entering closed loop, the truck will idle but when i open the throttle it bogs down and dies

engine specs:
1998 1 ton 350 block and pistons, stock crank, new timing chain, mid 90s LT1 hydro roller cam, stock 1989 TBI heads with stainless steel valves +polished runners, stock intake +polished runners, 350 TBI unit with adjustable regulator, holley projection fuel pump, new AC Delco pickup coil, new MSD cap, rotor, and coil, new Taylor spiro pro wires, stock 72 ram horns, 2 1/4" single pipe into thrush glasspack, new O2 sensor and IAC valve, stock 1990 K1500 350 ECM

notes: it has done this from when i put the engine in, but it got worse when i took off the 10 PSI napa fuel pump and put on the 14 PSI holley. also makes it worse if i try a 305 ECM (thought maybe it was flooding out). with a Tech1, it gives this info when it screws up:

O2 sensor 150ish mV
IAC 145
MAP 33 KPA 1.22 V
TPS 0.58V
closed loop (runs great in open loop)
ECT anywhere from 120-180*F
thats all the info i can remember, but i can try to find any other if needed

thanks in advance!
Josh

[Chris27]

I would have guessed faulty IAC, but you already replaced that. Is it possible the new one is faulty? My other guess would be that the injectors need to be replaced, if they are leaking fuel.

[Blue_71]

new update-- gotten worse, it'll start and idle but die withen 2 minutes, starts right back no problem and does the same thing again. it'll die immediatly if i even touch the throttle

chris-- i had wondered about the same thing so i hooked the Tech1 up to my 89, the differences are:
the 89's IAC only goes to 143, not 145
MAP stays around 28 KPA instead of 33 kPA
TPS stays at .52 at idle, not .58
O2 sensor stays at 455ish mV, but it wont come out of open loop (stupid headers)

[67-72williso]

You should be able to look down in to the throttle body and see if it`s getting fuel or starving. Just a though. That how I could till the 87 TBI injectors where bad on my offroad truck.
Later Willis

[Chris27]

You should be able to look down in to the throttle body and see if it`s getting fuel or starving.

Good call! I use a timing light and shine it at the injectors to shed some light on the fuel spray. That's also a good way to tell if your injectors are dirty.

[boostat4500]

Does the o2 voltage stay at a constant 150 or is it switching properly?
Should be jumping back and forth between there and 700ish.

[Blue_71]

these seem to spray strong up untill the time it dies, it seems to bog down first and then stop spraying. if i let off the throttle it'll start spraying again and idle fine.

the o2 voltage goes to 150 when it starts bogging down, and stays there untill i let off the throttle. when i let off and it idles again it toggles from 200ish to 700ish.
im wondering if its not an ECM problem, or maybe the port/polishing... whats throwing me is it wont do it untill its warm. i did manage to get it to run for about 20 minutes the other day, i unhooked the timing connector and kept advancing the timing untill it ran good. worked great untill i started up the hill in 1st gear (SM465 1st, not bulldog)
almost like its a warm engine load problem.. maybe MAP? what should that sensor do under engine load? it stays at a constant 33 kPA