97targa

Rear squeek could be shocks evn though they ride nice
Knock..Knock..sounds like the tranny bushing is shot. Easy fix.
Fuel Smell.....Multiple things are possible. here are few
--Fuel leak under hood( not under chassis)
--Catalytic Converter plugging up even though sensors aren't reading it
--Fuel filter
--Faulty Injector( Excesses fuel burning)
Computer Won't always pick up a rich mix(mainly lean mixes)
Check to make sure you actually have O2 sensors and not bypasses
With aftermarket exhaust cras tend to run rich without the change of plugs
Try to go to a cooler plug
Thats all I can think of

IWinULose

Welcome to the wonderful world of the T3650. That would be my guess on the knocking with the shifter and all. They are pretty sloppy trannsmissions. As far as the squeaking when going over a bump, check to see if the exhaust is rubbing the control arm where it goes over the axle.