Another Fuel Pressure Question

[3strats]

I've read post after post and thread after thread about fuel pressure, egr, weird surging etc... So i have gained a good bit of knowledge about the tests to run and what not. I believe i'm on some what of the right track, just getting a little overwhelmed. I have a 1990 5.7 tbi that idles fine (thanks to a new cts). After it warms to "operating temp" and is put under a load off idle, it stutters. I have noticed some backfiring through the tbi when its put under a heavy load. As i go down the road it seams to have a lack of power, more like something is holding it back. Cruise at 65-70 i can feel hesitation.

-Things done so far-
-New CTS and pig tail.(because it was the easiest least expensive place to start) Did help out some.
-New EGR Delco PN214-5073 Old one was not hooked up to begin with and diaphram would not move. Pulled and was pretty carboned up. Worth a shot eh! New one installed at idle, pulled in diaphram and engine dies. From what i have read this is supposed to happen. Also means passages are not clogged? Was getting SES light with code 32. No longer an issue.
-Pulled IAC valve and pindle was carboned up. Cleaned and did the best i could without removing tbi to clean passage where it seats. WD-40 and Q-tips till they came clean. Still get a little pulsing idle but not as bad.
-Plugs, wires, cap and rotor all new. Less than a year.
-Rented a pressure test kit from Auto Zone(Actron) Installed behind tbi which was a bear to do but figured it out. Did not come with adapter for fuel filter install. Turn key on and needle jumps up and fades away. Key off and try again with same results. Start truck and jumps up to 12.5 psi and is steady. Kill engine and needle drops to 0.

Ok. Heres my question in a question.

Since i have good fuel pressure, could this be the regulator or the split in the hose in the tank. I would think the system should hold pressure when the engine is killed, right? Would the split in the hose cause the system to loose pressure when the engine is killed?

Back to the IAC valve. Everyone iv'e talked to, out of this forum, says thats my problem. They always mess up. Is there a test? Or do they just "mess up".

I think i have covered all the bases. Mabey missed a few. I know its a long post, just trying to be thorough. Thanks for any advice i can get.