I ran into a similar problem on a V8 Camaro, and an 04 V6 mustang, both 5 speeds with new clutch and flywheels. Turned out the flywheels were the issue, not the starters like I had thought. Not really sure on the exact cause, but a new flywheel corrected it. I think
the ring gear was improperly welded on.
I'd try to loosen the starter up an wiggle it around a bit and re-tighten. Sometimes you can get lucky. Or maybe try a new starter before tearing it all apart, again.
I'll trade my 2 Fieros for it not sure you'd go for it...