Okay F150 fans... I need a little bit of help! My 2005 F150 Lariat has 186,000 miles on the clock... A very good Carfax report, and lots of service records... hers's the deal... Just repaired right side cylinder head. New cam, sprocket, rollers and lifters. Left side we replaced all the rollers. Camshaft was fine, and good lifters. Timing chains have been replaced previously. Installed new spark plugs, new ignition coils, and replaced the fuel filter, all injectors tested fine, and the throttle body cleaned... under driving condition, engine is good... 18MPG Highway... 15MPG plus in town... with 4X4 and 3.73 rear axle setup... however !... unstable idle, a little bit of throttle surge once in awhile, the throttle seems to be a little bit sluggish, in P it will act very sluggish and does not want to accept fuel above 3,000 RPM, and when slowing down for like a stop light, a slight stall wants to occur, but the engine catches it up. In P @3,000 RPM the engine has a very noticable surge but runs well otherwise... Service records are strong, religous oil changes with synthetic oil... am I looking at a possible fuel pump driver module failure... no DTC codes and a OBDII scan shows no codes at all... what's up with this girl ?