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My 09 silverado 5.3 4x4 has shifted hard into 2nd and some into 3rd for several years now. A few months ago I decided to fix it. Codes were for transmission control solenoids, module, oil pressure sensor, misfires...etc. codes like P0700 P0717 P0521 P0523. I replaced all 3 shift solenoids, oil pressure sensor, and immediately the truck shifted like new again and it lasted for a few days or a week. And it started shifting hard again. Really hard. It's so frustrating. And it's throwing all the same codes again. Recently, my truck started misfiring so badly the entire truck was shaking. It was running on two cylinders. All of the ignition colis were failing all at once and the truck was not drivable. Btw, I just changed out those ignition coils, plugs and wires just two years ago, all Ac Delco plugs/wires and duralast ignition coils. So anyways, I replaced all of the coils plugs and wires again this week and the engine no longer misfires, running on all cylinders again. And for a few hours after, there was zero hard shifting now. It was running great, like new again. Shifting smooth as could be. But after making it into the city and hitting traffic lights and stop signs, it didn't take long for the very hard shifts to come back. I've read on this and have been dealing with this in time and parts for so long now. I've read about ground wires could be the cause of all of this. I have replaced everything the computer has suggested, and for a short time after the repairs, the truck would run like new. But the hard shift always comes back. I know there's people out there that have had this same problem. I've read a lot about it but without actually finding the grounds for these specific sensors, I've hit a dead end. The issue just keeps coming back as it's obvious there is a root cause I am not getting to. Please share any knowledge or experiences on this topic. And any knowledge of the location of these grounds may be at. Thank you!