RPM Gauge sticks and jumps

Hey everybody! New to the neighborhood. I've got a 2002 V6. It mostly has just cosmetic work...clear diamond euros, billet grill, billet antenna, tint, flame gauges with blue coloring. Only engine mod is a CAI. I was at the track last nite... just hangin with a friend. On my first run I only ran a 11.25 on an 1/8 mile track... pitiful!!! I ran again and noticed that my RPM gauge was stickin and jumpin around as I was goin down the track and it didn't really miss.. just ran poor. Any ideas or suggestions very welcome. Also any ideas on any low cost upgrades would be much appreciated. Thanks!!

It started hesitating just here recently. I've had the car for about 5 months and had all the fluids, plugs, and plug wires changed when I got the car. It doesn't do it all the time... just here and there. This is my first Mustang, so I'm just looking to see if anybody else has/had this problem. I'll get my gauges reset. I hope that's it. Thanks.