87 2l loses power at the top of each gear

New member here. Just bought a B2000 and it bogs down at the top of each gear (5 sp). I'm thinking carb, but any other places to check. Stock carb and was running without an air filter when I got it.

First replace fuel filter; in engine compartment, passenger side, hidden somewhat under air cleaner, on fender well.

Plugged catalytic converters.

I'll swap the filter. How do I check the converters?

An easy way to check is by pulling the 3 rubber hoses from the pair tubes, that go into the air filter housing. It'll be loud, but if the condition goes away, your cats are plugged.

I'll check it out. What's the fix? Replace, or delete? No emissions to worry about here.

Unbolt the exhaust and beat out the ceramic with a hammer and drift bar, or pipe.
There are two cats, so you'll probably have to do them both.

Mine is cat-less. I did exactly what SinCity described. Use new gaskets when installing. The gaskets for the front converter are special, a little tougher to find, but part numbers have been posted before.

Thanks for the help, I took off the cat and it had already been emptied out. I thought I was going to have to dig into the carb. While I was down there we bent and plugged the reed valve lines coming from the cat area and plugged the hose coming from the exhaust manifold. Started it up and it's all better. Must have been something we did, but I'm not sure what. Another question ; is there supposed to be a gasket between the downpipe and the front catalytic converter?