Yeah they flat out SUCKED. No other way to say it
I fought several. They seemed to be better as years went by, the 90s and 91s were definitely less headache then the 88s. I had an 88 d100 w/ 318, and no matter what I did with it, it was my worst mileage I've owned to date. Dis better with a 78 d 300 dually and a 79 full time 4wd, and I spent so much money "good after bad" trying to improve it, I'd have been money ahead to swap back to a carb. I sold that truck as a result. Always something wrong with it. EVERYTHING in comp/EFI system replaced multiple times. My son's 90 w250 wasn't much better, his 89 ramcharger was bad enough it did get converted to carb and runs SO much better than it had ever been.
Worse than lean burn. Too bad because the rest of the trucks around that crappy system were pretty good.