Welcome to 2CarPros. Your description sounds like the exhaust is plugged partly, likely by pieces of the flex pipe as it came apart. A quick way to test this would be to disconnect the Y pipe at the rear connection and see if the power returns. If it does you will likely need to check the converter and see if it's plugged or seriously restricted. You might be able to remove it and blow the restriction out if it is something like pieces of rust. I doubt it is farther back although it could be in the muffler if it was driven a while, that is because the exhaust heat also dries out the pipes and pieces and driving with the leak lowered the heat through the system and the interior of the muffler could have corroded and blocked itself.
Dropping the pipe at each joint is a quick test.
Friday, October 11th, 2019 AT 5:23 PM