1-2 shifting problem

[JROB46]

I have a 1993 Chevy Silverado, 350, 2WD. It has a 4L60E transmission. I just started having a problem shifting from 1st to 2nd. When accelerating the RPM's go way up and won't shift until I let off the throttle. Then it shifts into all other gears normally.
If I accelerate slowly. it will shift into 2nd at about 16 MPH. It will then shift into all other gears normally.
I have replaced the Throttle Position Sensor, flushed the transmission and replaced the filter and fluid. This made know change in performance.
I am now suspecting that it might be the 1-2 shift solenoid. But before I go any further, does anyone have any other thoughts about what it may be? Does anyone know for sure if going to a shop and having diagnostics done will be able to determine the cause of the problem? The check engine light is not on and everything else works fine.
To all that may reply, I appreciate your help.

[j cAT]

Originally Posted by JROB46

I have a 1993 Chevy Silverado, 350, 2WD. It has a 4L60E transmission. I just started having a problem shifting from 1st to 2nd. When accelerating the RPM's go way up and won't shift until I let off the throttle. Then it shifts into all other gears normally.
If I accelerate slowly. it will shift into 2nd at about 16 MPH. It will then shift into all other gears normally.
I have replaced the Throttle Position Sensor, flushed the transmission and replaced the filter and fluid. This made know change in performance.
I am now suspecting that it might be the 1-2 shift solenoid. But before I go any further, does anyone have any other thoughts about what it may be? Does anyone know for sure if going to a shop and having diagnostics done will be able to determine the cause of the problem? The check engine light is not on and everything else works fine.
To all that may reply, I appreciate your help.

replace both shift sol. if one is worn the other will follow.

cost is about 25.oo ea. these are the same.