I have a 1994 z28 and i just got a full tune up and got the intake manifold gasket replaced when i started to drive the car away from the shop it wouldn't shift into second i had to let go of the gas pedal so it would shift into second. and it would hit 40mph and not go above that. i took it back to the shop and told them about it and they switched out the oil pressure sensor for a new one. took the car out again and it was doing the same thing. what could the problem be? it wasn't doing this before. will changing the tranny oil and filter solve this? any feedback will really be appreciated.

 

I dont think a filter and fluid change will fix anything. will it go into any gears other than 2nd. u said it won't go over 40 mph. I would be thinking of a bad ,missing,loose ground wire for the trans shift solenoids. need a little more info