Sounds like your problem has more to do with your chosen shop than the
motor. Could a cam timing issue set the MIL? It's a long stretch and you
would notice some serious running issues first. As far as repairing the
threads... I've been using helicoils for 'bout a million years now... freely
available at automotive stores, cheap, effective - might add some to the
labour but not something that will break the bank. In my experience,
teething problems aside, the 4.0 SOHC has been quite a success for FMC.

From where I sit, the system in the US is broken (this will raise some "free
enterprise" ire) and sadly in need of repair. There is no requirement for
knowledge or skill...... a hammer and a half inch wrench makes you a
mechanic... Add that everyone is bargain shopping and p*ssed because
Chevette pricing means Chevette service.... "No way I'm going to a high
priced mechanic because the cheap guy bent me over the service counter...."

Add that the labour laws in the staes seem to be nearly non-existant......
we have some pretty firm minimum standards here and, thankfully, my employer
goes above and beyond the call of duty.

If your problem is as you describe (still wondering how a bolt inside the
cassette could do this), find someone that understands the word "helicoil"
and he/she can help. Sounds like you've been victimized by someone either
unknowing, uncaring or both.

HTH