That's exactly what I did. I picked up several of those "problematic" systems back in the day. For free. All fully functional. All completely out of adjustment and totally screwed up by some "factory trained" mechanics. One of them has been running trouble-free on my 3.0 for fifteen years and darn near 100,000 miles.

Owned mine since '13 never had to do anything to the mfi.

An AFR meter makes all the difference between now and then. It takes all the guess work out. Start with a CMA (Check, Measure and Adjust) to make sure you are at the right starting point and adjust from there. Really not difficult once you know what the adjustment do (and there are only a few).

Chris
73 911 E

I think all of the add ons and bandaids that were on the pumps, esp the decel system, caused some quirky drivability issues back in the day, and I think more with the Ts than the E and S. Maybe because we saw more Ts or maybe their lower compression was a hinderance. Carbs were the easy, economical way to go then. Saw an invoice for my 72 from 1995 when I had a 2.7 RS space cam installed. Other than a couple of belts and pulleys, never a hiccup. No decel system on it. Bob