Not driving smooth, jerk while shifting

[anupgs]

I have a 2004 G35 Automatic, 23500 miles, oil changed ever 3 months at the dealer, K&N air-filter installed at 22,400 miles, tires rotated twice at 10k & 20k and in-cabin filter changed at 15k. No other maintenance done so far.

I have noticed for the past month, the car is not smooth as it use to any more. I can feel vibrations in steering even at park and while driving it gets worse. I can feel minute vibrations in the accelerator and brake pedal as well. Has anyone else had similar experience?

Also what has been happening recently is that if I am driving on a flat road at 40-45 miles/hr at 1500-1700 RPM and there is a slight upward slope, the car jerks quite bad. It feels like the gear is downshiffted, but the car is pushed forward as if it misses or something. Anyone else experienced this? If so, what might be the issue?

Thanks for any insight.

[Q45tech]

40-45 miles/hr at 1500-1700 RPM and there is a slight upward slope, the car jerks quite bad..

Are you using nothing but Premium Fuel, does your fuel contain ethanol?

Classic indication of the engine not delivering enough torque at these low rpms...............what happens when you tune a small engine [for car weight] to produce high rpm power and try to maintain good MPG.

Also fuel quality [btu output] may not be up to quality used for design [common US problem]. Also dirty valves and spark plugs from dirty fuel deposits.

Try a can of BG44k from dealer if this improves the problem proves a fuel/injector deposit issue.

The major problem is the AT gearing allowing overdrive to occur at such low rpms and the locking unlocking locking of the TC lockup clutch.

Do you routinely blow the soot out of engine weekly or does it just get lots of city traffic?

[infinititech1]

sounds like the complaint for a valve body