Chevrolet Repair: 93 k1500 305 automatic, throttle position sensor, intake manifold gasket

Question
i just finished changing the intake manifold gasket on my 93 k1500 with a 305 engine, i also cleaned the throttle body with a spray cleaner while i had it off the manifold. After i reassembled everything the truck started fine but i had to adjust the timing.  When i took it for a test drive the transmission did not shift out of first gear until 2500 rpm or more and then it lost power and acted gutless. Is it possible that this is a throttle position sensor problem?  I can't find anything that I missed and the transmission worked fine up until I decided to finally replace the leaking gaskets....... thank you

Answer
I am trying to remember if this truck has a detent cable.  If it does you probably left it off or have miasadjusted it somehow.  Also if your timing is still incorrect it will cause the truck to run like that.  When you set the timing did you disonnect the timing connector under the lower passenger side dash?  This puts it in base timing.  Also plugged exhaust system causes this type of problem GOOD LUCK