Hi guys and girls

Wondering if i can pick your brains please

Think it's time my 16v golf may need a tune up but not so sure.
Problems are:-
1) Blows out black smoke when you floor it
2) Drinks so much petrol even when driving like an old man
3) Polish the tailpipe and a couple of miles down the road it's as black as a industrial chimney
4) When starting up when it is hot it's lumpy and ticks over on less than 4 cylinders for a little while until you rev it up
Any ideas?
Cheers peeps
