That plastic upper manifold was an issue. They had issues with backfiring and it blew the manifold right off the top of the motor.
GM realized that the manifold was an issue and started replacing it with a different manifold.
When you replaced it, did you use the original plastic manifold?
If you did, let me know and I will find you the updated manifold. They were known for warping under heat especially at the EGR. If the valve hangs open, it will overheat the manifold.
Sunday, March 29th, 2020 AT 3:39 PM