2001 Blazer will not shift gears... Need help!!
 

I have a 2001 Chevy Blazer V6 4.3L 4x4 auto with 124,000 miles. It starts fine and goes into gear fine but it wont go any faster then like 5 mph. It kinda sounds like its in N when when im hitting the gas. I hooked it up to a my OBD II but all it said was a TPS sensor i went ahead and changed it but still no luck.... Any Ideas? im hoping its not the transmission. Just wondering if anyone else has ran into the same thing. Thanks.