Hi,
My 1990 Olds Eighty Eight recently started to shake while it idles and when
it's driven at all speeds.  The engine starts easily but shakes and stumbles
under throttle.  So far I've replaced the spark plugs, fuel filter, and PCV
valve.  Nothing seems to help.  Sometimes it smells like gas, so I took it
to Canadian Tire to check for gas leaks but no leak was found.  I put a
bottle of methyl hydrate through the tank and a bottle of injector cleaner.
I also sprayed Gunk intake cleaner into the throttle body.  The engine just
seems to keep running worse the more I drive it.

Any suggestions are welcome!
Jeff