I recently bought a 01 grand cherokee with a 4.0 ran great and suddenly it falls on its face lack of power I'm suspicious of catalytic converters clogged changed plugs ran great for a bit then on its face again pulled injectors cleaned and new seals it's struggling to make power any suggestions would be helpful

 

If you have a IR temp gun you can check the exhaust temps before and after the cat. should be hotter behind the cat. If it's cooler the cat is bad and could be clogged. I have been told you can undo the bolts on cat and slightly separate it to see if it runs better but it will be loud for sure.

Max

 

I removed the cat and have plenty of power next inline is to but a header on and a highflow exhaust system I've also replaced the injectors thanks for your input