Help! Fixed intake gaskets now trans is throwing codes

Common issue with the valve bodies in those cars. You may be able to get away with just replacing the solenoids, but sometimes the valve body needs to be replaced. It's kind of a c*ck to do if you don't have a lift, but it is possible. Unbolt the left side of the cradle, loosen the right, unbolt trans mounts, remove left cv shaft, sway links, droop the cradle down, remove side cover bolts, then you may have to raise or lower engine/transaxle assembly to weasel the cover off to get to the valve body. Get the parts from your local gm dealer, give the valve body a cleaning (I use brake clean), and hope for the best. The issue usually is the solenoids get debris in them (happened to my parents volvo too with the 4T65E). Not a big deal, just time consuming.

When you debating what car to ditch, I was going to mention this issue to you, but I didn't want to scare you away from an otherwise decent car.

At any rate make sure you didn't pinch any wires while doing the intake too.

I think you need to double and triple check your wiring -- specifically the grounds. It's just too coincidental that there were no problems before but 3 electrical (solenoid) codes after the repair.

Exactly what DRIVEN said, go over the electrical with a fine tooth comb, check ANY linkages to the transmission. Man it's hard to say with modern vehicles because the electrical system are very complex.

I agree with the other guys on wiring it is just to easy to have this issue after taking the top part of the engine apart, I had a mechanic fix a car of mine some years ago and pinched a wire and after a week of driving the wire broke and the car wouldn't start, the wire was one of the main spark signal wires from the ecm. I would just triple check the wires if it where me.

Make sure u have pwr comin in and goin out at the trans fuse. Alot of times the ign switch that pwrs the trans fuse sh*ts the bed. Bad contact points in the ign switch. I believe the wire is white in color. I usually just piggy back into another wire that has key power.

Another thing check the round plug on the side of the trans. All those sol's have the same pwr source and the r ground switched by the PCM.