Load Up Or Misfire Under Load

[poolschool]

Hi everyone. New to this forum and im after some advice. I have seen an Mk2 focus St with 69k on the clock for sale here in Spain. I have driven it and it seems to load up on small throttle openings and hesitates.It runs fine every where else in the rev range, No smoke or any nasty noises.I must point out it has been tuned with a re map and a bigger intercooler and at least a back box and filter.This was done by MOTORsport Development. It also seems to shake when accelerating which is coming from the front. This shaking is similar to a previous facelift focus Latvala i had last year. The Latvala is just a jazzed up Trend 1.8tdci which is a Spanish model only. Is it a common fault and any ideas?

The engine is the most worrying as i've heard about engine blocks cracking. I don't know if this is a common problem or not? Anyway its a decent deal and i have a grand or so to fix it if need be. The main problem is that they are useless at this sort of thing here in Spain. They are no where near as clued up as the UK tuners if you can even find one!

Thanks in Advance

[poolschool]

Quick update.As posted elswhere on here. The problem was a turbo boost pipe split and a dirty MAF. All done and only cost me €85 at a ford dealer. I take it back about the spanish mechanics. I found a good one. Also he has never had an st in before as they are rare here in Spain. Im one very happy geordie.