CLK 320 Power loss

[icekool]

hi,
my clk320 avantgarde MY 2000, has suddenly got a power issue, sometimes sluggish in the morning, take the key in out a couple of times and it's fine, but on the motorway last week put my foot flat and the engine went flat, wouldn't go over 40mph, i had to pull in behind a caravan! (the limitor was not on!). once i've taken the key in and out a couple of times it seems to run ok after that untill the next morning.
i have been reading various of the threads and found a few with similar issues. some mention the MAS, could someone tell me what that stands for, and the location, going by the other postings i will need to check my ht leads and plugs, but can't seem to identify the postion of them in the engine, - the haynes manuals do not cover the CLK320 - any other publications available that any one knows about.
i'm currently restoring an MGB GT 1973 and am ok with removing parts and replacing them, but the clk engine is a mine field that i hope to step through without putting my foot in it!