Lumpy engine

[Baj]

I went to look at a T5 today.
First off, cheers guys, your posts about the crankshaft seal saved me a few bob as I left without buying (it was a little ropey anyway).
The engine idled fine but when the accelerator was pulled it was lumping.
It sounded fine but it felt like something was off-centre (a bit like when your wheels need balancing but in the engine).

For future reference, was this an ECU issue or something more mechanical?
Either way, expensive?

[theravedaddy]

could be anything as simple as a knackered plug/lead right out to head gasket or complete motor.difficult to diagnose without being there to pull bits off. if you dial in the cost of fitting a 2nd hand motor as a worst case senario and still get a cheap car then go for it-or run away!