Hi folks, I've been cruising around here for a bit, and have had a couple of Focus in the past, but now I'm looking at jumping into the ST170 darkness

Anyway, I've read a couple of advice threads, and just need some clarification of things.

IMRC, this will sound like a dumb question, but I am completely clueless about these cars so what is it? What does it do? Is it the ECU?

I've seen a couple that have EML issues which according to threads on here may relate to IMRC, but otherwise cars appear sound.

Apart from the dreaded metal worm, the only other thing that appears to be dodgy is the clutch, and I did get the clutch done on my diesel estate a couple of years back so I know that can be expensive.

I was tempted by the one that 1-PD has, but it's just too far away from me

any comments would be welcome