i have a 92 hatch, and once i start up the car the RPM's are high, around 1 1/2. After warming it up, the RPM's go really low, to around 1/2, to the point where it almost stalls.... the car shakes and im not sure how to fix this... i do have a sub and amp installed but this happens even without my head unit being on.

Another question, but regarding the sub and amp, when i turn the bass high, the rpm's go lower and lower....would a capacitor solve this problem?

Thanks in advance.