2005 chevy malibu has a slight jerk feeling when it is in 4th gear going at a constant speed and I can notice a slight bounce on the rpm gauge. Also if in low range using plus and minus buttons, when setting gear range to 4th it seems like it does not want to shift from third to 4th

Is your tach (if you got one) or speedometer. jumping or bouncing? Check engine light? If so i would be suspect of vehicle speed sensor.

If the engine has a rough idle you know you have a miss-fire or other problem with one or more cylinders.
When you shift into overdrive the engine is working harder than in normal drive because of the lower torque/RPM.
So any slight miss under normal conditions will be magnified in overdrive or with the ac on.
See if you can nail down the cause for the rough idle.

This is a rare one and can be tricky. Since your rpm gauge rises back up when you increase your acceleration slightly but you feel no jerking of acceleration then this tells me that a speed/rpm senser either has a bad connecton or the sensor itself is going bad when the engine reaches an optimum heat while driveing on the highway. Since you feel no acceleration when you slightly press the accelerator down but yet the rpm gauge is increasing back to normal, the throttle body sensor may be compensating for the failed speed sensor/failed sensor connector. Please get your uplander diagnosed properly first to confim this.

Given how little it's being driven there's a good chance it's just a vacuum leak or a bad modulator. neither one of these are very expensive to fix.

When was it last tuned / serviced?? faulty / worn out spark plugs.

Try shifting into neutral and pressing on the brake while turning your key. Sometimes when I'm in park my shifter doesn't make the switch that says I'm in park, if I turn the key...nothing....cause my car "thinks" it's in gear.

sounds like you may have a problem with your speed o gear in trans.

check tps (throttle position sensor) because it has an effect on transmission shift issues.

there are so many sensors nowdays that cause the same problem.---a bad throttle position sensor causes,:transmission shift issues,bucking, jerking, idle surging, engine cut off,hesitation on take off, surge while cruising down highway. a code will not allways set for a problem.

This could the problem with misaligned wheel ,please get the wheel alignment done and check for any extra wear the type on the any one side which cause this problem....


Good luck...