the engine in my '92 roadmaster wagon that i just finished putting back in has a bit of an issue. it starts up and idles nice, revs up in park/neutral no problem and sounds good. once its been running for 5min (ish) it develolps a heavy surge, giving it throttle does have some effect but you really need to caress it, eventually no amount of throttle play will cure it and it just stalls. wait a couple seconds and she starts right back up and does it all over again. the issue is the same with the engine hot or cold. no check engine light

whats been done in the last 4 months:
engine re and re
lt1 cam swapped in
headers
headgaskets
new valve springs
valves relapped
new ignition module
wires, cap and rotor
new gaskets throughout
a/c delete
AIR delete
No cats, just mufflers.
rebuilt tbi
new 4 wire o2 sensor
cold air intake
fuel pressure bumped up (stretched regulator spring a bit and tang moved up)

at first i thought maybe a fuel pressure problem, now im thinking tps perhaps?

heres a video, it had a real abrupt stop here and it kinda scared the sh*t outta me:

 

Was this a 350 car to start with? Are your injectors the 61# 350 units with the part numbers ending in 206?

Have you set the timing with the timing bypass wire disconnected?

Your engine changes really should have no issue idling ok on a stock chip.

 

Stock engine. Stock injectors. I'll get back to you on the injector model theyre not 9c1 or bb injectors though. Yes the est (I think that's what its called) was unplugged when the timing was set. I'm running about 10 degrees advance timing which it seems to like before the surge starts.

 

What happens when you unplug the o2 sensor and try to run it? Have you checked for vacuum leaks. 10* IMO is a bit much for a stock swirl port head engine. Have you tried backing it down to around 4*?

 

IIRC the lt1 cam swap thread for lo3/5 says 8 degrees or more. Runs pretty rough at 4 degrees. With the o2 unplugged it runs even worse once warmed up. If I hold the pedal at a consistent rpm like 1500 or 2000 the engine will slowly start to lower down in rpms unless I apply more gas. If I let off quickly it'll stall or almost stall. Pretty confident its a fuel pump/pickup hose issue now.

 

Sounds like it is running lean, which will make it surge. You might have done more bad than good stretching the fuel pressure regulator spring and raising the platform without the help of a fuel pressure gauge.

0-4* should be plenty of timing when the ECM advances the timing. With the timing bypass wire disconnected set the base timing at 0*. Shut the engine off and reconnect the bypass wire.

My ported 193 head 355 with the LT1 cam and a ported TBI unit worked well at 14 psi fuel pressure with the timing set at 4* advance. On premium fuel it liked 6* and 14.5 PSI. This was running on a stock 1992 fullsize van chip.