Here's a couple links to video's showing my sticking throttle. And a couple things that enable it to close properly.
https://youtu.be/kgT8Mum5fhQ
https://youtu.be/h1SSb0Gd38E

Quick symptoms list:
* Slow application of the throttle, causes it to stick partially open.
* Turning off the engine, allows it to close properly.
* Unplugging the MAP vacuum line, allows it to close properly.
* The throttle returns properly every time when engine is not running.

More Info:
This is not the first time I've had this problem. I've replaced MAP and TPS (twice) trying to get this to be fixed. None of those replacements fixed it. It's intermittent when driving...sometimes it'll have error codes. I suspect that it's frequently sticking, however under a load, and with the doghouse installed, I think I'm just not noticing it.

Last time it was fixed (summer 2015), my mechanic adjusted the TPS position to a lower voltage and that fixed the problem. I have NOT touched the TPS mounting screws since then.

Recently the engine was rebuilt and reinstalled. The problem reoccurred at that point. I've got ~800 miles on it, and the service engine light came on three times. Codes include:
42 Ignition Error
33 MAP sensor high
22 TPS sensor low


I asked for help with this before on a different forum.
http://tunerpro.net/forum/viewtopic.php?p=14808#14808

I can log info from tuner pro, I also plan to to check vacuum and TPS voltage when the vehicle is NOT running, and will follow up with a reply or edit this post with the findings.

General info:
1995 Chevy G30 HD van
CA Smogged - passes visual and sniffer (set base timing back to 0, from the Harris recommended 10deg for test)
350 TBI
Summit AL CARB legal heads (design similar to vortec...with improved geometry/flow around valve stems in chambers)
Stock exhaust manifolds
L31R short block w/ stock cam from a 1996
ECM: 16197427 BNKM
Modified bin (from Brian Harris)
Upgrades from Harris' recommendations...regulator spring, ultimate mods TBI, upgraded fuel pump.
~15k miles on upgraded TBI w/ larger bores/butterflies, modified gasket, and intake. The shaft and bushings are good, there is NO sticking, and the torsion spring is strong.