I was poking around and doing stuff the other day after looking for the cause of my sticky wastegate.
I cleaned the contacts for the coil (with a diamond file) and re-crimped the contact tabs to make them squeeze the coil posts tighter. Also loosened and re-tightened some engine ground straps and injector ground straps. I don't think they changed too much, since I'd done them before.
WOW. Seems like a big difference in off-turbo (black zone) driving (hard to judge turbo performance given the sticky wastegate). Also noticed a possible 1-2 mpg increase. Gonna put in a new air filter tomorrow and see if I can track a consistent increase.
I do still have this annoying, unpredictable every thirty seconds misfire..... so frustrating! The alternator (which was rebuilt) is still making the belt jump, so I should charge up the battery and pull all the accessory belts and see if it still does it. Feels like a dead miss and only seems to do it at idle. That should be another post though.

Happy bricking
Will

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1990 740 Turbo, on its way to stock specs, maybe beyond