Any TBI troubleshooters out there?

[Chevy3+3]

I'm having a tiny problem with my'88 V30 454 tbi truck not running quite right. its hard to put my finger on. To describe it best is it feels like when trying to accelerate under normal load that my power comes & goes a little. Almost like my fuel & air mixture is changing or my timing is searching. The trucks base timing is at 6-7 degrees BTDC (computer wire unplugged). The truck idles great. Runs good but not great at WOT. The exhaust smells RICH but don't notice any black puffs from tailpipes. It never backfires but occasionally has a weird floaty hollow pop sound from tailpipes at idle. Its very faint.

To describe it best is a slight hesitation just off of idle (occasionally), somewhat sluggish come & go acceleration through midrange almost like I could have a vacuum leak. If I push the throttle more is seems to come out of the sluggish acceleration until I hold the throttle stationary again. It almost acts as if its responding to getting more air for a split second when I apply more throttle. At idle and WOT it runs the best.

I've tried a new distributer, old working distributer, 2 new Delphi fuel pumps, new fuel filter. Triple checked timing, Triple checked and cleaned all grounds, I have sprayed every possible location searching for a vacuum leak and have found none. I've checked the EGR valve and it holds vacuum. The truck doesn't display any codes or check engine light.

I'm wondering about the TPS, MAP sensor, IAC valve or EGR solenoid malfunctioning?

Any thoughts or ideas would be appreciated. Thanks in advance