Hi and thanks for using 2CarPros.com.
Based on your description, it could be a few things. The first thing I would suggest is to check for trouble codes. You may have already done that, but just mentioning it in case.
https://youtu.be/YV3TRZwer8k
If no trouble codes are found, I would then check for an engine vacuum leak. You have replaced a lot of things already but did not mention if you checked. Here is a link that shows how it is done:
https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge
If that checks out okay, then I would suggest checking for excessive back pressure from the exhaust, which could be the result of a plugged converter.
https://www.2carpros.com/articles/bad-catalytic-converter-symptoms
https://www.2carpros.com/articles/how-to-test-a-catalytic-converter
Okay, with that being said, let me know what you find. If you already checked these things, let me know. Also, let me know if the problem started all at once or over time, if there is an odor from the exhaust, if you checked for a head gasket issue, engine compression, smoke from the exhaust. The list goes on. Anything you can tell me that may help.
Let me know.
Joe
SPONSORED LINKS
Friday, August 10th, 2018 AT 7:30 PM