o.k., here's a weird one, '97 4wd 4.3 auto, 170,000 miles, 3.42 gears, fresh tune up, and by tune up i mean plugs, wires,cap,rotor& air filter. tires proper size and fully inflated. no troble codes and has no issues when warm. but when cold and first driven, the first time out on the road every morning when the transmission makes the 1-2 shift it stumbles, coughs and about falls on its face, then picks itself back up, goes through the rest of the shifts without issue and is fine the rest of the day. you could even come to a stop right after the 1-2 first "choke" of the day and its fine the next time it makes the 1-2 shift. oil level is a little bit over the full mark on the stick, but i wouldnt think that would be the issue. egr maybe? it did do this before i did the tune up, heck, its why i did a tune up! its done it to both me and my wife. she gently accelerates, i tend to "enjoy" the torque more than she does and just mash the throttle until i set the cruise control when i reach highway speed. even though this motor has some pretty high miles, i was surprized to find a good compression test result, 180 on 4 cyls and between 175-180 on 2 cyls. very close to even on all 6 and pretty high in my opinoin for the miles, has used very little oil in the last 1,000 miles since oil change, dad says its usually time to change it when its down a qt, but i dont really know what he goes by as far as interval. anyways, is it just "cold-motor" related? maybe there is such a big step in the ratios between 1 & 2 that when cold its a bit much for the motor to adjust to without choking on itself? almost seems like its backfireing through the throttle body when it happens, dont think thats possible, but it seems like thats whats going on. did get a new fuel pump a year or so ago, has the "spider" fuel injection setup (sequntial multiport). i can live with it, but im confused about why its doing it.

 

I am having the same problem with my 93 blazer. Did you ever find out what the problem was?

 

no, it still does it. if i let it warm up a few minutes its fine. and on the oil consumption, it was at the 4,000 mile mark after a oil change before being down 1/2 qt.. i think its just a big jump in gear ratios within the transmission between 1st and 2nd that it just cant quite make the transition when the engine is cold. trans fluid level is still good. just one of those little annoying things i guess. had a astro van years ago that would slip as it went for the 1-2 shift in cold weather, that was the older 700r-4 automatic.