Gearbox fault cropped up

Hi guys and girls. A new problem has cropped up on my P38a 2001 4.6 on lpg. My 1st instance was in maccy's drive through and the engine gave a little rev. I was in drive with foot on the brake. The car tried moving a little. This has happened a few times. At the same time The display has beeped once and gave me 'gearbox fault'. Car goes into limp mode, 3rd gear with no shifting. Using my nanocom I have the code 'P1884 Can message PHOEHE invalid (ffh)' I lose the transmission indicator on the display also. On occasion the car revs drop to the point it will stall but doesn't. And just the once it has stalled.

The fault clears once the engine has been turned off and the display shows the transmission once again.

Does anyone know what the code means? I've googled it to death but struggle to find a definitive answer.

All points towards maf sensor, and temperature reading fault

Never heard of this on the P38, but about 3 years ago had it on the Merc, it was the valve block electronics board on that which had failed but the symptoms were almost identical.
I thought the box in the p38 was fairly bomb proof until the later L322's?!?!?
If the MAF doesn't cure it, it might be worth a gearbox filter and fluid swap?

Just to follow up, I got the AA out to it as it wouldn't start in the Shell forecourt. On their diagnostics it came up with the Crankshaft position sensor had logged a fault. The chap said with the symptoms I had described it will almost certainly be that. Parted with £63 to euro car parts and it was half an hours work to change it and woof, all is good.

Thanks for your efforts chaps.