No power when accelerating, struggling to get to 60 mph

[Teekay]

Hi guys
So I made the mistake of thinking that after all the trouble I have had with Fiats I could easy buy a 1.2 polo to work
on and get back onto the road... clearly not a smart move.
I bought a polo that displayed signs of a burnet out valve. engine shake ect. I took the head off to work on it and to find the valves were still
good. I cleaned up the head put it back changed the chain as theold one had jumped a tooth as well. so I thought the problem was solved.
but still I have the acceleration issue. when you put your foot down in second It hardly moves and it struggles up hills.
Looking for any help as what it could be.
car is a 1.2 BMD 55 e 2007

I changed the spark plugs and the coils but alas it still bogs down and wont pull. any help would be appreciated
also to add no EML

[Crasher]

Start with a code read, print out, code clear, re-run and another code read/print and post the results. Did you check the axial play in the exhaust valve guides? These are extremely prone to wear.

[Teekay]

Hi Crasher thanks for the advice!
Sorry I have my dissertation due in so I had been a bit busy so I left the car for a while. I came back to it and started again from basics
I checked fuel spark and then looked at the exhaust. After going through it I came to the conclusion my Catalytic converter was blocked.
Found one at a local Factors and plumbed it in now the car is up and running, It was an interesting little project and got to learn a lot about
the 3 pots. in the end I just had a hate for the car and gave it to my girlfriend .

Thank you also for your answers in other posts, I have been following your very useful advice that led me to finally being able to fix the issue.

Cheers
Takunda