The engine is a b234f with a freshly rebuilt head, along with new plugs, filters, leads, all vacuum hoses etc, plus flame trap, MAF, IAC cleaned thoroughly. It has been running smooth as butter for 10,000km. It's the same igniton/fuel system as a standard 240/740/940 lh2.4 volvo, thus same troubleshooting applies.
It had a no crank/start issue two weeks ago which was a semi drained battery (load tested) from the alternator brushes being worn. So I replaced the alternator brushes, the battery terminals, charged the battery fully (load tested again, passed) and she cranked very healthy, but took longer than normal to start, which I put down to lack of fuel as the front end has been on jack stands for two weeks.
Drove it to some back roads with absolutely no issues on the way, after 15 minutes I noticed I was losing speed, and couldn't accelerate, when I pulled over it stalled.
I tried to start it again, and it exhibited all the typical signs of a failed MAF, poor idle, no power etc. So I unplugged the MAF, it ran rough as guts, but stayed alive. Turned it off, plugged MAF back in, started again, and it ran perfect, now with a lambda light.
Checked for codes when I got home, the only code was MAF sensor, so I cleared the code, started the car, and it was like nothing happened, but I haven't taken it for another drive.
Because I drive 65km to work, I just want any suggestions as to what it can be.