Its seems lately Im on a roll with my vehicles falling apart or something wrong IMO. (except my 93 of course)
My 95 at times had a real rough idle, bad enough it would shake the bed. So I found a bad fuel line and replaced it and also the overflow valve and filter and valve adj. Seemed to help the idle. Yesterday we went on a 4 hr drive towing a 2500 lb trailer and now not at idle but from 900 to 1400 rpm just sitting its real rough with a consistent weakness in 1 cylinder or something. It seems to put out a lot of soot for just a short trip compared to my 93. Black tailpipe, rear of truck side,bumper. it starts pretty good, has to crank for a couple seconds and we got 16 mpg towing that little trailer and around 20 empty. Pulling a fairly long but not real steep grade 5 gear will hold at 1800 rpm but thats it. I cant tell if the AFC has been readjusted or?? any ideas where to start? Im gonna check all the cyls with a infared temp sensor tomorrow at this rpm and see what I get. If I need injectors what would you reccomend? I dont need anything like PODs , marine type??
Thanks again.

 

some times re seting the timing or bumping it a few degrees helps with a "stumble" like you describe

I have a friend with a 97 and it would idle fine, top end fine, but as you would go from idle to top end it would stumble and blue smoke a bit

bumped the timing to 16* and it all went away

 

Read the post I placed on the 0-65 tops topic, your problems sound very similar to his.

However, if you have not adjusted the valves in the last year, check those and pay particular attention to the exhaust valve lash.

The other item to check is the little rubber doughnut in connector from the wastegate to the AFC housing. If that gets loose the AFC will depressurize and start holding the rack follower from opening. The same thing can happen if the diaphram in the AFC develops a crack or leak.