MustangAudioNoob

I've Been having issues with Betty for over a year now and it's driving me nuts.
Problems:

• Sometimes when I start it up the idle is rough
• Car shakes back and forth at low levels of acceleration
• Reduced power/fuel economy
• Idle drops from 750 to 450 then goes back up when stopped in gear
• (probably not related) the tranny sometimes hesitates before it shifts

I've tried:

• Replacing plugs, wires, coil pack, fuel filter, pcv valve, o2 sensors
• Using seafoam, injector cleaner, tranny fluid changed, and cleaning the throttle body

Doesn't give me any codes and I don't have the cash to go trying every solution.
Thanks for any help.

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01 3.8L/ aftermarket dual exhaust/ CAI/ 2 12" Subs