Wondering if u could help me out with this one. i have a mk3 fiesta 1.6s its basically got the lean burn XR2 engine the head has been ported and flowed on the intake ports aswell as them being straigtened out. i only done a bit of constructive work to the exhaust ports since i couldn't see much a way of improving them since they where square. it's also had a 30 thou skim.

My problem is the car seems to miss or strugle a lot under load around the half throttle 1/4 to 2/4 throttle mark it does it in 2nd when the engines cold, when it's warn it's only really in 4th and 5th but u can notice it in 3rd aswell under certain posistions. it's only when accerating and it starts missing and only gets better when u let off the throttle or push it down to full throttle and then it's ok, i've put new plugs init and its just had a new altentator so the coils getting the right voltage, the HTT leads test at only 8000 ohms so they are fine. i always use optimax, also the intake manifold has had the water chanell blocked of to allow it to run cooler could this be the problem. or could it be pinking or a carb problem it be like this ever since the 30 thou skim, its still got the TLD carb on it i've adjusted the mixture to get it to idle better would this affect it since this is only supposed to be the idle mixture on this carb. also the timing is still standard on the mark.

PLEASE HELP I'VE BEEN TRYING TO SORT THIS OUT FOR SOME TIME NOW