2001 PT Cruiser with SuperCharger stuttering when switching gears

[RandomCarProblems]

I am helping out my mom.
She just bought a 2001 PT Cruiser with an aftermarket supercharger and aftermarket 5-speed installed (she got totally taken advantage of at the dealership but that's another story).
It drove up fine for about 100 miles when it was driven on the freeway, but has now started to stutter like it's not getting enough gas, but it still has a quarter tank. The speedometer also starts going haywire when it starts to stutter.
I took it into a repair shop and they said they didn't get any error codes when they scanned the engine and they suspected it had something to do with the supercharger, but they won't touch it since it's an aftermarket part. I've called around to several shops and they all say the same thing, that they won't work on a car with aftermarket parts.
According to my mom the dealer showed her a way to unplug the supercharger so she can get it to pass SMOG inspection in CA, but of course she doesn't remember what he showed her. I'm trying to figure out if I can just unplug it and my mom can still drive it around.

[maxwedge]

Ok, so is the car in California? What kind of supercharger can be "unplugged? Many things can cause the symptoms you describe, gotta find some who is willing to check this out. If this was sold in any state that requires smog testing, the selling dealer is required to pass it at time of sale. Btw, welcome to the forum.