My son has a 96 with 4.0. It is a former BLM truck bought in auction. It has about 70k total miles on it. Overall the truck is in great condition however the power seems down ad the MPG is poor. I suspect plugged CAT's.

I can do the work to replace these two cats (in series) but, would like to consider a single performance CAT and a better "cat back" pipe and muffler.

What do you guys recommend?

 

'Am I on the wrong board for this question?

 

the cats could be clogged but do you know if the truck has ever had a tune up done?

 

For the cats to plug , you would have other , more pressing issues ,ie. burning excessive oil/fuel. Something has to be wrong for them to plug up.
First see what,if any, codes are stored in the PCM.
And no , the CEL does not have to be on to have a code stored.

 

if a tune up wasnt done could that lead to the cats plugging?

 

doubtfully.


are the cats holding alot of heat?

 

Cats plug due to unburnt fuel/oil/antifreeze. This causes the cat to over heat and deform inside,partially closing the exhaust passages.
They do not plug on an engine which has no oil blow by,head gasket leak,or over rich condition and is running the way it should.