I am the second owner of a 1998 GMC Jimmy 4X4 SLT 4dr, 6 cyl, automatic transmission, that just rolled over to 100K miles. The orig owners only used the vehicle to pull a boat during summertime and I was told it was garaged when not in use. I bought it in 2001 with 28K on it and have predominately garaged the vehicle. Around 60K I noticed that when it shifts from 1st to 2nd, it would buck into 2nd, making acceleration difficult coming into oncoming traffic However, if I lift up on the accelerator pedal as it would begin to shift, it would go into 2nd without any trouble at all. I have had the transmission fluid changed around 65K and then around 88K I had it changed again along with the filter, my mechanic also added a softner, but it still does this.