New MAF sensor/spark plugs/something else?

[CycloneAsh]

Dear all
I come to the forum freaking out about my 2002 147 Sele (done 175000 ks).

Recently I've been having these problems:
- loss of power, especially when accelerating
- engine makes a crackling sound when under heavy load
- fuel economy has gotten significantly worse

After doing some research the potential causes appear to be either a failed MAF sensor or the car needing new spark plugs, and I was planning to get both checked out and whatever needs to be fixed at service time in the next few days.

However since yesterday in city driving I've also had:
- smoke coming from the clutch
- the whole engine vibrating before grinding to a stop, and i've had to turn it off and restart.

I feel like this is a clutch problem, but is it a matter of an adjustment or (please god no, this is my daily driver and I'm a bit financially strapped right now) needing a full replacement? Or just more sensor issues?

Thanks in advance, I just want to know what to expect before I take it to get checked out (FWIW, I usually take it to Alfamotive in Sydenham, NSW)

[Mick A]

Ah, have you checked the engine oil?