Hesitation upon acceleration. the engine does not respond in a linear manner when pressing the gas pedal.
1.constant jerking sensation occurs before vehicle shifts into lower gears while at relatively low speeds and throttle settings (25-45 mph, stop and go city driving, maintaining speed). 2.when minimal increase in power is needed or a mild grade is encountered, additional throttle pressure seems only to result in loss of power until the transmissions shifts into some lower gear. the vehicle then accelerates too rapidly, followed by the need to reduce throttle pressure ' or apply brakes - which in turn causes the transmission to shift back to a higher gear. the sequence then repeats itself. 3.note: poor drivability issues are reduced when the engine is cold. also keeping rpm above 2000 helps. 4.depending on driving conditions, the vehicle will accelerate well while shifting up through the gears but seems to loose power as rpm drops, forcing a downshift or increased throttle position. 5.when under slight engine load, the suspension seems to amplify road bumps, to the extent of finding bumps where there are none. this condition is reduced while at idle throttle settings and coasting. 6.a recent drive through the mountains prompted me to resort to manually shifting the transmission to improve drivability because of hills and curves. 7.i frequently resort to driving in s4 except for interstate driving so as to keep rpm above 2000 to improve drivability. 8.frequently the engine feels to be missing, resulting in vibration through steering wheel and accelerator pedal. 9.on four occasions since ownership the rx has suddenly and expectantly accelerated for unknown reasons, forcing emergency breaking. this is an extreme safety issue. 10.when using cruise control (~65 mph) and if the set speed is reduced a couple of mph, the rpm jumps to 6,000. 11.transmission slow to choose a gear when accelerating into traffic.