2002sentra

Hi, I've had this problem for about 6 months now and don't know what's causing it. I have a 2002 Sentra GXE Automatic & around 93K miles on it and bought is used last year.

The gas peddle gets stuck and makes it hard to accelerate. I have to press down harder than usual to get it going, when it gets over the initial sticky-ness, then it accelerates. This can get dangerous when it's raining when the wheels would spin from slipping on the road.

I took it to my mechanic, but since he could not reproduce this consistently, he had no way to fix it. Does anyone here have any similar experience like this, and if so, what can I do to fix this.

Your help is greatly appreciated.