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Idle '99 TL

So I recently moved to Cambridge, MA, and I’m experiencing my first New England winter. It’s been a joy and a pleasure so far. I went on vacation for Christmas (I went south). When I came back, I was worried my car (a '99 Acura TL automatic) wouldn’t start. It did start, but now manifests some problems while idling. When I have it in park or neutral, it jumps from the normal idle level up to about 2000 rpm, then falls back to normal, then jumps back up once it hits 1000 rpm. It does this for as long as I leave it in park or neutral.

When I have the car in drive, it idles higher than it normally does and accelerates without me pushing on the gas pedal.

Any ideas what the problem could be here? Also, for any Cambridge/Boston area residents out there, do you know of any reputable mechanics in the area?

The first suspect for high idle is vacuum leak to the intake manifold. The vacuum leak can be where the intake manifold mates to the cylinder head(s), or other attached parts. Vacuum hoses can deteriorate and leak. Some components, which operates on vacuum power, such as the brake booster, EGR valve, cruise control, may become defective and lose vacuum.

I can almost guarantee it’s your IAC (idle air controller); have it checked out first. Common problem with 2nd gen. TLs.