Hesitation / Low Power Below 2K RPMS - No CEL

Recently bought a 86 LE with 149K miles on it. The van had been sitting a while so I replaced the air intake tube (was mostly duct tape), air filter, plugs, wires, cap, rotor, fuel filter, and ran some gas treatment through it. Fires up immediately (hot and cold) and runs great in town and on the highway except for the lack of power below 2K RPM's. Runs out great on the highway with no issues. Trans shifts from park to drive slightly rough but it shifts crisp and smooth where expected otherwise.

No check engine lights.

My initial thoughts are a plugged catalytic converter? The exhaust has a pretty strong odor but no visible blue or white. No losing coolant or burning oil.

Appreciate any input.

does it sound muffled? like its trying to breath through cotton wool?
another possibility is one of the silencers has broken down internally. have a look into the back box with a torch and see if you can see any glass fibres loose and jammed up in there.
I've had that happen quite a few times on cars over the years, especially after they have been sat ufo ages or had a change of lifestyle.

cats can break down but id be checking the silencers first. theres a metal holed pipe the gasses pass through internally surrounded by glass fibre wadding. when its s at up the pipe rusts through and it escapes blocking the exhaust.

The muffler on this van needed to be replaced so I cut it off. Took a drive (surprisingly not that loud without it) and still had the same low power below 2K RPM's.

So I decided to remove the Cat... ended up having to cut it off.... and put in a temporary 2inch flex pipe... Took it for a spin and it's much better.

when i had my exhaust rebuilt, i pulled it off where it connects at the intake and drove it to the shop. i was worried the whole way i'd get pulled over for noise pollution :LOL2:

Was able to put on a new catalytic converter and muffler this weekend. Used universal parts with 2 inch ID so I could do lap joints for better stability. Made a huge difference in the performance, and of course, sound. First plugged cat for me.