Gauge Cluster

I had put in Flame gauges into my 2000 Cavi about 6 months ago. Ever since i put them in the gas gauge hasn't been working right. If i put a full tank in, the needle would go all the way around until it got stuck on the temp gauge. About 2 weeks ago the gas gage started working right. I turned the car off and back on and the temp gauge went to where it usually is, then it just dropped as far as it could and it hasn't moved since. If any could help me, give me some info on how to fix it so i don't have to go out and buy another instrument cluster and more flames gauges, i would really appreciate it. Thanks