Starting problems L-series

For a while now I noticed the car was having problems starting when cold. But recently it's gotten worse. It used to start almost immediately, but now it needs a couple of seconds cranking before stuttering to life. Also the first couple of seconds, it isn't running very smoothly and black/grey smoke is coming out of the tailpipe. Give it a couple of rev's and it's fine. And if it's been driven, no problems at all.

I'm suspecting the fuel filter to be dirty/watery of the pre-heating relais to be bad (it's been cold lately). Maybe a dirty MAS?

Any thoughts on how to fix this?

Check glow plugs, clean tank sender and replace fuel filter, put in some injector cleaner and go for a good thrash!
15 quid for a fuel system spring clean!

Tank sender, that one I forgot. Tnx!

How do you clean tank sender ???

I haven't looked yet, but it's supposed to be in Haynes. I'll make some pictures when I get round to it this weekend hopefully...