I have a 1999 s10 blazer that just started to do this when you take off it seems to want to go into third then fourth gear right away. if i manuale shift one works great two gets a little sluggish then three and four are real sluggish i have not tried to go over forty so i dont know what it will do at higher speeds. I just drove the blazer again it seems to be going in lockup right away and doesnot come back out with out manual downshift it even stepping on the gas all the way will not make it drop back out of lock up any one have an idea what it is?

 

Could be shift solenoids. Its not too bad a job to change them out, and they're pretty cheap.

 

ok i had a tranny shop hook the truck to there scanner and they said it is shifting from 1 to 2 to 3 to 4 and into lock up before it even gets to 20 mph they said they have never seen any thing like that and do not know what it is but thing its in the wireing or computer nothing with the transmission itself. If any one has a good idea i would appreciate it.