i have a 99 s10 blazer
when i go from p to d the truck starts out in drive,not 1 or 2
if i shift it manually,it works fine

 

Um, are you sure its not starting out in 1st gear?
D= 3rd gear provided your column also shows OD, which is 4th gear.
Why do you say its starting out in 3rd gear?

 

well im not positive but,,,,if i take off in drive,the blazer shudders and has no power,untill i reach 30mph then everything is fine i cannot feel this car shift at all,or downshift
it works fine if i start in 2 shift to 3 then drive.

 

A 3rd gear only condition could be caused by a lack of power to the transmission, an electrical short, or solenoid not being grounded properly.

Go over all of your fuses making sure that they are all still intact.

 

Couldnt it also be a faulty torque converter kyle?

 

Doesn't really sound like a faulty converter to me though. The shudder on initial take off combined with very sluggish acceleration from a stop leads me to believe that it is starting off in a higher gear. If the torque converter were bad, you should also have an engine that was rev'ing up while getting the vehicle moving.