You can test for a clogged cat with a vacuum gauge on the intake manifold. It will start up with a decent ammt of hg and then vac gauge will drop down. Or unbolt the cat on the manifold side and go for a loud ride. Now doing a compression test is the easiest way to check for bad rings, valve seats, or a hole if you are that unfortunate. Bottom line is you can test all this yourself with < $50 of gauges.

89 v6 Raider 5spd
89 v6 Montero auto
86 TD Trooper