Sounds like a timing problem, how was the cam timing done? Once that's solid then you need to do fuel pump timing and then dynamically set it.
You say you changed maf? Must have a 1999/2000 car with a hot wire type as the older flapper box ones are long long long out of production, if you find a supply please share, i could do with one.
Maf might still be the problem, recently went through 4x maf sensor until i got one that worked (2 were genuine bosch, but reman instead of new) on another car. Went mad taking loom apart looking for breaks that weren't thre as was the maf all along.
Older msa 15.7 cars don't really work with obd despite the plug looking like one, so you'll never get any useful codes without the right machine.
15.8 cars you might get some codes but again not all of the..
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