ive got a 2.0 mondeo engine in my 1.6 si and it was running fin up until a couple of weeks ago and then one morning i drove down the street and it was really really lumpy, i took it home and checked all the plugs no problem, i thought it was the spark plugs and leads so i changed them but that didnt fix it and then i noticed it was spitting out water so i thought oh great the head gasket has gone, i was kinda stupid at this pont and didnt do a compression test and just ripped the head off cause i was really annoyed, had it skimmed, cleanned up the block and pistons, bolted it all back together and now its still missing when you rev it and now its got a sticky tappet, i blame my engine builder friend who pulled it apart and said it was ok to come apart and then put it back in the head,

i just need to know where to go from there really, anyone had any problems similar or got any ideas im really stuck and can not think what to try next!!

PLEASE HELP ME