2007 jeep wrangler with 3.8 bogging down and missfire on highway then clears up then comes back .also sluggish with no power then back to normal
First step, ask your shop to check the diagnostic computer for p-codes. None? Then my guess is either a problem with the ignition system or the catalytic converter. If this happens only when engine is hot, and you feel lucky, you could try replacing the crank position sensor on a flier. Best bet though is to start w/ a proper shop diagnosis.
A lot of things can cause this. Is the check engine light on? if so, post the codes.