1993 pickup 4x4 w/22re. Just started doing this yesterday. Engine starts and idles fine from a cold start, go to drive and as soon as the temp gauge gets to about 1/8th of the way up I'll get sudden bad hesitation/stuttering. This only lasts 8 - 10 seconds and clears up then will run fine from then on. Never happens any other time. Only as the engine warms to that certain point. Any ideas? I replaced my water temp sensor about 15k miles ago and the o2 sensor at the same time. Check engine light doesn't seem to be throwing any codes.

 

I guess I should start with the water temp sensor, I can't think of what else would be doing this as it seems to be related to temperature

 

Check the ohms on the AFM. Once your truck gets to a certain temp it switches from closed loop, to using the sensors for the different operating ranges. Could be going rich, then after a couple minutes the O2 sensors lean it or richen it up for propper operating. Also, the Air temp sensor is built into the AFM. This site will show you how to check it. http://www.4crawler.com/4x4/CheapTricks/AFM/index.shtml

 

Thanks, will check it out tomorrow, for some reason the page isn't loading right now for me.

 

You could try copying and pasting the address. Its working for me.