OBD P0301 code - hesitation/lagging
 

Hey all --

I have a 2001 A4 Avant with the 2.8L 30-valve engine and automatic transmission. I bought the car last year with 80K documented original miles, and I LOVE the car. It's exactly what I need, and it's been dead-reliable for me. I've never had an Audi before, so I don't really know my way around its technical bits, but I'm reasonably handy with vehicles otherwise.

About 6 months ago, I had the 80K-mile timing belt service done, along with a full tune-up (including new plugs).

A few times a week, I drive about 30 miles each way, along a windy mountain road. A few weeks ago, I noticed that it started having some lagging/hesitation issues, but only within the 1,100-1,600RPM range which, coincidentally, is used a lot along that road. But when idling, it's perfectly smooth, and at all other RPMs, it's likewise smooth and strong.

I thought it might be some crud in the injectors, so I dumped a bottle of injector cleaner in a fresh tank of gas. That didn't seem to make any difference.

And then last week, the "check engine" light came on. I tested it with my OBD-II reader and it showed a P0301 error code; just that one. Supposedly, this means a misfire on the first cylinder, although I usually associate misfires with a sparkplug that's not working at all (except maybe at high revs), but as I said, otherwise, the engine idles smoothly and the rest of the powerband seems to be unaffected.

I haven't taken it any further than that yet; I was hoping to get some experienced advice first -- particularly to find out if this is a common problem, if it's likely to be a serious problem, or if there are any quirks I should look out for, such as parts that are prone to failure.

Am I correct in assuming that the first order of business would be to pull the #1 plug and inspect and/or replace it?

Could vacuum hoses cause this? -how 'bout the ICM?

Is driving it while I try to troubleshoot it, likely to endanger the engine? (Don't worry; I won't quote anyone on that, should something go wrong after all.)

Any advice would be appreciated.

Thanks!