986 S problem at idle, engine won't rev and shakes, battery disconnected

[Homeboy981]

May be a bad ground somewhere…possibly that "GPS device" that is not connected to the rest of the car's grounding system, huh? With the ground pulled, you should NOT STILL BE PULLING AMPS from your battery.

My factory stereo experienced similar problems when I replaced the HU and tried to use factory wiring, and original wiring was taken out in favor of wiring I KNEW WAS GROUNDED PROPERLY.

A dead battery or corroded battery posts, faulty ground circuitry, or a MAF about to croak ALL would be producing similar "spotty" problems. Your problem seems intermittent - it does NOT happen ALL the time. The guys have provided AWESOME and CORRECT troubleshooting information, given the responses you have provided.

It may be a job for an experienced mechanic to trace back some of your wires, replace the MAF, replace a faulty battery, clean posts or check the wiring. Batteries DO fail, even new ones. Insurance companies GPSs are made for the masses…how long has that thing been on there?

Your problems, as described, DO NOT seem to 'go by the book' of troubleshooting….unless some bit of information eludes us!

LOOK HARDER you will find a bad ground, visually check the MAF - clean it with MAF cleaner, clean the battery terminals (even IF you have a new battery there can still be crud on the posts-check it).

Your answer lies within. If not, there is no shame in going to the Indy (would not trust the dealer) and have him try 'specific' items, as described.

Good Luck!