1st time poster, long time mustang owner here. So I just purchased my first SN95 GT Convt. It only has about 64K miles on it. However, it has a hesitation problem. This problem occurs at low speeds and at times while trying to accelerate at highway speeds. Furthermore, the vehicle seems all-around lethargic. I have observed the following modifications: SVO intake, under drive pullies, 160 or 180 thermo (judged by eng temp), 373s, shorty headers, 65mm throttle body, flow master cat back. I have performed the following services since buying the car 1 week ago: oil change, new plug wires, Berryman's 2 step combustion cleaner, redline in gas, changed pcv-metal screen-grommet, cleaned MAF w/CRC MAF cleaner, cleaned TB w/CRC TB cleaner, Rad & Block coolant flush, multi meter check air intake temp sensor, removed MAF screen, replaced Air Filter, Replaced Fuel filter, checked fuel pressure at rail (40psi line off). I checked 2 spark plugs: pass side rear/driver side frt; both looked new. I have noticed: High pitched whine from fuel pump. Also, there is NO check engine light popping. Please help. Any insight out there?