Help.

I have a 99 maxima with about 60,600 miles and don't know what to do next. Ive been having problems with my acceleration. It seems to be an intermittent problem as no one is able to fix the problem.

When I accelerate and deccelerate, there is a vibration in the pedal and sometimes the pedal is really hard to push. Sometimes to press the pedal takes a lot of effort. What is this? Even on the highway at steady speeds around 80, the pedal has a little free play(like the cable is rubbing on something). It feels like maybe the throttle cable is sticking and is causing all this vibration. This is even after replacing the cable and getting a full throttle service done.

On top of this, my trans is hesitant when it is shifting. From stop to start, the car accelerates and at about 40 to 60 mph, it feels like it doesnt want to follow thru with the shift causing my car to jump back. Its like the engine and trans are not in tune.

I never got a full tune-up, - will bad spark plugs cause any of this or what about old trans fluid cause i havent had a full flush yet. Can someone advise me what to do. Cause my car has been acting up since August and for the money Im paying each month, Im going to trade it in and get something else. My max is a big headache.

Anyone max owners who live in philly, NJ, or DE - you can test drive it and let me know what you think is wrong. Thanks.