try disconnecting the oxygen sensor to see if anything changes.
also, disconnect and block the vac line going to the the evap canister.
where is the exhaust leaking from?
i too have a set of working but second-hand sensors including PCM and alternator under the back seat. as well as a spark tester, and noid light.
how does it drive if u pull the fuse for the TCM and take it for a spin?
when confronted with bat shit crazy gremlins check the earths
