c16se lacking power

[scottyb]

hey guys. ive got a corsa b with a c16se engine, i blew the last one up only 2 weeks ago and finally put a new one in yesterday, ive homed out all the bores cleaned every single thing that could be cleaned and it ran a treat but now its lacking power but only in low revs its almost like its got a broken injector as it backfires through the exhaust, but as soon as you pick the revs up it runs fine and is only really an issue in 1st 2nd and slightly in 3rd gear!
does anybody have any ideas?

[sri888]

might be a broken piston ring. does it breath heavy ?

[scottyb]

no not at all mate

[TonySR]

You say you've had it all apart, is it timed up correctly?

[scottyb]

yeah ive checked it over again and its perfect, im all out of things to try