Thanks again. In retrospect, I never should have ok'd the work on the intake gaskets nor the supercharger nor the new water pump, tensioner/idler pulley & belts. I think it was pretty unnecessary & threw off the harmonic balance of my 65k miles Bonny. My fault for mentioning the rattling charger & some fluid leaks on my last inspection. Now
I know from here that a rattling charger is pretty normal & ok.
Anyway, the Pontiac dealer couldn't find any problems, even w/ the strong gassy smell, because they couldn't get an SES code now. At least they didn't charge me the $100 for diagnostics.
Tech remarked on invoice that he checked gas tank, lines & injectors on rack & no leaks found. Service guy said no vacuum leaks, though fairly possible they didn't do a real thorough troubleshoot.
I tried again spaying carb cleaner around tube & hose but no rpm rev-up. Looking at the EGR valve, it looks like even a novice like me could put one on. I'm thinking of getting a used one & trying it. I'd be paying twice as much for a more thorough diagnostic.
Is trying another EGR for about $50 the way to go? Are there installation instructions for it on here?