Surging
 

1991 Chevy S10
4.3L TBI
TH700R4

I need to update my miles on here since the truck now has 262000 miles on it.

So recently the truck doesn't want to fire right up if I take a short drive [less than 10 minutes] and once its warm it runs fine but at 40 to 50 mph it stutters and shudders a pinch until I give it more gas. I thought it was a trans issue of it slipping but it did it off idle in park.
Is it time to replace my TBI unit? I recently replace the IAC and it ran better for a month and now this issue popped up, do the IAC's go bad or are known to fail? I could clean the one I pulled and reinstall it. Tank was cleaned and new pump and filter were installed 2 years ago with zero issues until now and I still get 20mpg hwy.

I only run 92 octane non ethanol gas.