engine ??

[vectra2002]

hi, by any chance anyone got a bottom half of a z18 engine they dont want goin cheap lol ?

[diablo666]

vectra2002 has put a x18xe1 bottom end and a z18xe topend in a vectra B 2001 - z18ex (same as 1.8 vec C engine) car runs but has a misfire on cylinder 4.
car is basicly a vec C 1.8 z18xe but with a z18xe1 bottom end.
misfire is worse on tickover but not to bad at high revs.
tried another coil pac, injectors, plugs, MAF
cat has been suggested ?? is this possible to cause a misfire on cylinder 4 ?

ty in advance