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During a winter refresh, I decided to replace the cracked original AMP fuel injector connector housings as well as the housing where the wiring connects to the MAF (7 prongs). This requires extracting the pigtails from the old housings and inserting into the new. I carefully marked the wire orientation but now the car runs on 4 or 5 cylinders and barely at all if I connect the wiring to the MAF. So I need to trace the connections. Anyone run into this before and can offer diagnostic advice? I confess to being a beginner when reading wiring diagrams.

After referencing different wiring diagrams in the manual and using a multimeter, I determined wires 6 and 7 were switched. Both wires go from the MAF to the ECU.

The car now starts but any application of throttle causes it to stall. The idle speed hunts as it warms up and it will not restart unless it sits overnight or I pull and clean the fouled plugs. Could I have ruined the ECU or the MAF? The coil tests ok and the plugs have spark. The ballast resistor connections are correct. Any thoughts are greatly appreciated.

It's an AFM, Air Flow Meter, not a MAF. Anyway, #1 is ignition and FI are completely different systems, so one working and the other not is as it should be. I've gotta guess you have another wire(s) in the wrong place. Since it's a 528i you can always hook up a meter to the O2 sensor to confirm it's running lean as I suspect it is. Not sure where you go with that, but any info is good. Did you fry the ECU? Maybe, but I doubt it. It's mostly a box of resistors for logic. Think, did you do anything else to it, wiring wise? Any chance you switched a non injector FI connector?

Thanks Mike. Too many generations of cars so thanks for the AFM clarification!
I haven't considered it may be running lean as all 6 plugs foul with gas. Checking the fuel injection connection is a good suggestion. Also, the ECU connector on the wiring harness has 2 rows of ports - the wiring diagram shows 1 row. I counted all of them on the connecter as if they were in a row. Is that correct?

I dunno on the ECU connector, but I think it's numbered. Real faintly. A 2 row connector sounds right though.

All connections double checked and correct so I started reading the blue shop manual for ideas. In the emissions section there’s a symptom / cause chart that details exactky what was happening; starts but stalls under throttle. One item on the checklist is a failed brake booster vacuum hose. Hmmm, I was waiting to install the master cylinder and brake booster in case I needed to,pull the intake runners and had capped the vacuum port on the intake manifold. Decided to go ahead and install the master and brake booster, new vacuum hose and port valve. Started right up and runs fine. Go figure.

I take a screen photo of your final post, solution after the litany of entries to get there. Keep it, print it for the files.

Too bad it won't make it to the club Technical FAC list, simplified, check brake booster, etc., and experience knowing few questions inspire looking through previous posts.

When you refer to the blue manual do you mean the hard copy or the on line version with the fudge crud photos ? No offense intended, I have so much fun with the cool post dude ( checked the BBf, AKC, dbl in case the flb was shorting ) Oops, I meant the ACK.
And looking for the," Emissions," section in the manual.

Must be where I can't find my glasses.