Yes and yes
You are overloading the factory speakers.
The 1997 Grand Caravan Infinity amp can be located behind the stereo system. The stereo system will need to be removed in order to access the amp.
Usually, Infinity Sound makes them. If you bought it second-hand it might be an aftermarket stereo
Infinity speakers
Cars with 'premium' sound systems from Infinity (or Bose) always have their own amplifiers hidden in your car. These amps are specificially designed to work with the factory head unit and speakers. If you want to upgrade your head unit you would be well advised to replace ALL the speakers and amp with aftermarket units as well. It would be especially tricky otherwise the Infinity setup in Galants have 7 speakers, including a center channel speaker in your dash.
The GMC stereo has amplified rear door speakers. When wiring up the aftermarket stereo, connect the blue wire on a GM aftermarket harness to acc power and the speakers will work. I did the same thing for mine about 5 years ago. Good Luck...
Needs a wiring harness, can't just put in an aftermarket stereo without re wiring the speakers etc.
The amplifiers are on the infinity speakers. Each speaker has its own amp.
you have your wires routed wrong
For the best rated brands of car stereo speakers, Kenwood, Sony, Infinity, and Rockford Fosgate are among the highest rated. The prices are also reasonable.
Amplifiers are on the speakers in the door. Otherwise its just in the am/fm/stereo unit
The 'fader' setting on the stereo may be set to 'rear'. The front speaker wires may be damaged or disconnected from the stereo or speaker.