I have a brand new long block from ford well it has like 10k on it now. Did not run right when I got it back. After taking it back to them twice; Once to fix the rear main that still leaks and once for an idle problem which they said was cats and maf. I finally found a loose lower intercooler tube the bolts weren't even tight enough to stop the flange from rattling, after tightening this I finally got the car to run a 15.2 which isn't bad. But I expected better. I also have 4.30 gears and a 10% march pulley, removed air silencerand a 3" cold air intake. Last week for no reason I just got an irradic idle with not CEL it will die at stop lights it is so rough I have 10hg in park and 5 in gear sitting in the drive way. I can still get a good eleven to twelve pounds out of it which is all I ever got with my pulley which I don't comprehend. Would a miss from a plug or wire effect my boost or does this have to be a blown gasket or vacuum leak. 6 weeks ago my friend and I removed the blower and clamped all the vacuum lines and tightened the blower tubes. Any help would be great thanks.