My '06 Focus 1.6 is suffering from hesitation during heavy acceleration mostly around 2000 rpm. Initially I replaced the coil pack, which almost completely fixed the problem. A few months later, it suddenly got worse. I replaced the spark plugs, and again, the problem was almost completely fixed. To try to fix that last little bit of stutter, I've also replaced the HT Leads. This has made little to no difference. If anything, it's more noticeable at lower rpms now, around 1200. The only part of the original ignition system remaining is the ECU. Can anyone suggest another problem that may be causing these symptoms? Otherwise, is there a recommended technique for testing the coil drive outputs on the ecu? Cheers.