I have a 98 astro
and the tranny has been shifting rough, I got the code P0751
Shift A CKT PERFORMANCE Solenoid stuck off.

What solenoid is it and where is is located
and any suggetions on how I need to do the repair

thanks

The transmission oil pan must be removed to access the shift solenoids and wire harness connections. Are you experiencing a harsh or delayed 1-2 shift?

Yes 1st to 2nd gear is very harsh, the shifts are normal in all the other gears

When was the transmission fluid and filter last changed? It should be done every 36,000 miles. A very common problem is the 1-2 shift valve will bind in its bore in the valve body. If changing the fluid and filter doesn't improve the 1-2 shift, find a transmission shop that's familiar with the 4L60E transmission. Ask them if they are familiar with the repair procedure. GM is aware of the issue and they have a technical service bulletin addressing it.