TBI Idle/highway trouble

[snowball]

Hi all,

I'm having a bit of trouble with my 90 burb, R1500, 350 TBI 2wd.

This has been an ongoing issue, for the past few weeks. Starting to get annoying.

Truck hunts at idle. When I get to a stop, initially fine, but as I wait for a stop light, it gets progressively worse. RPM's drop and rise and drooop, and rise and drooooooop... it's even stalled a few times.

At highway, sometimes, it feels like for a second, the injectors stop firing. gives you that thump and your head bops forward.

And sometimes, during load I get a backfire. not sure what end.

and sometimes, I'll keep my foot on the gas pedal steady, and it will downshift, and bog, and upshift, and downshift, and bog and upshift.

and sometimes it runs like there is nothing wrong. strong, full power, full acceleration. no issues.

Yesterday it was "cold" for texas. got into the mid 40's. Started the truck, and stalled right away. repeat. stall. put my foot on the gas steady. start, release stall. start again with pedal, romp on the gas. runs rough and stalls at 30 feet away as I back out of the driveway. repeat, and got her going.

I checked the CTS when I got home that night. 242 ohms and dropping. 30-40min later it was ~450ohms. so it looks like its working right.

TPS was replaced with an ACDelco. Ran for 3 months and one of the reading was stuck at 450 Ohms. Replaced it with one from oreily. looks good. both sides no dead spots.

Fuel pressure is 13PSI, 2 year old carter pump and new filter.

No codes stored.

Any ideas would be greatly appreciated.