Transmission slips but when i shut engine off and restart it will work for a short while then slip again. any thoughts?

Take it to a qualified repair shop .

Sounds like the the clutch are wore out and will need a rebuild

When you say the trans fluid is fine, is it a clear reddish color? does it smell burnt? also does your check engine light come on at all? how many miles are on the car? GM usually recommends a trans fluid flush at 100k miles under normal driving conditions and at 60k miles under more severe driving conditions. it sounds like there may be an internal problem with the bands or the pressure may be low. I would recommend taking the car to GM dealer for a better diagnosis as it sounds like it will continue to slip when it gets to normal operating temperature and it will get worse in the future. another option is to add 2 bottles of Lucas trans fix (48 ounces total) to the trans fluid but you will need to pump out that much fluid if the trans fluid is already full so you don't over fill it. the lucas trans fluid additive does work pretty good unless their is serious internal damage already done. Good luck!

Possible, but make sure you have correct fluid level. Start car and let idle for 15 minutes, fluid level is checked with engine running.

Have you changed tge trans filter in the box as yhis could also xause this as ifvits blocked or dirty it can restrict the flow of oil

does the tranny slip or not.
only you can look and see, got a tachometer or a trained ear?
if it slips and wont go that is tranny issues
if it dont slip and dont go , that be bad engine power.
no one on earth can go from here until that is answered.
job 1.

Try Lucas no slip up to three bottles.remove difference.

All slipping transmissions do that. The turbine gave up the ghost, and if not repaired soon, the additional strain on the transmission may cause it to fail too. Seemingly turning off the engine allows the trans fluid to cool off a bit, and there is also additional pressure when you restart the engine, giving the transmission the possibilty to work decently for a few yards, but as soon as the fluid overheats again, it starts slipping.

You may wanna try replacing the soleniod pack mounted on the front of the transmission.U may have to purchase it at a local dealer or napa.If that does not repair your issue you may have to install a used transmission.

Check the fluid level and make sure it is up.If o/k then suggest a trans service which will have the filter and fluid changed. This could be your problem.