1995 Accord vibration at certain RPM band

I saw a few posts that were close, but none of the answers matched what I've tried so far. So here's the history. It's a 1995 Accord wagon with the 2.2 VTEC motor. I bought it at 80k and have no major problems until recently. It's now at 165k. I had the transmission rebuilt about a month (500 miles) ago. A week after that, a piston on one of the rear calipers got stuck, so I had those replaced. A week after that, I started getting an odd vibration at most speeds and only when trying to maintain that speed, not speeding up or slowing down. Within a couple of days, it was vibrating when going up through first and second gears pretty bad. However, the more gas you give it, the less likely it is to vibrate (which feels like the engine is missing). So, I took it back to the transmission shop and let them keep it for a week while I was out of town. They narrowed it down to an 'engine problem', but got no error codes. The check engine light has never come on. So, I thought they were dodging a bad rebuild and tried blipping the throttle at home. Sure enough, it gives me the same vibration at home while in Park or Neutral, so it's not the transmission. It's between 1,750 and 2,100 most of the time and seems to happen more when the A/C is on. It does not do it all the time, just most of the time. A feather foot on the gas while trying to maintain 25 - 40 mph makes it go crazy. A lead foot or no foot usually makes it go away. A local Midas shop that does light service and has done most of the little I have needed replaced the plugs, wires, dist and cap as they said it was a cylinder not firing. Well, it did it again as soon as I picked it up. Six hours of head scratching later, they have no idea. So, I took it to another local shop that has done work for friends and is a full service place. They had it all day today and can't figure out what's wrong with it. Any ideas? Any recommendations other than an exorcism are welcome. I had a motor mount replaced a year ago and have no idea what the vacuum situation is, but I think they checked that today. I'll have it back to them on Thursday when I can leave it all day again and find out then.

Wonder if it has an injector putzing out at low throttle demand?

Have you done a compression check? This will tell you if you have a cylinder not firing which one mech. has told you. Since you have done the electrical tune up and eliminated that as a problem you may have a valve that is bad. Compression needs to be done wet and dry to determine the condition of all cylinders and find out if it is a cylinder problem or eliminate the cylinder as a problem. Have you run any injection cleaner through it recently? This would be the first and easiest thing to do. Use techron as it is one of the best. You may need up to three tanks full if it is an injector problem. Walmart has it for 5.98 a bottle.

Wonder if it has an injector putzing out at low throttle demand?

Thanks for the responses! I finally have an answer, and it wasn't any of the suspected issues. It turns out that three of the four EGR ports were completely clogged with carbon. A little cleaning and voila' ! Good as new. Of course, there was mechanic time to dig that far, but I'm happy to pay for labor when they find the problem and fix it.

Here's a good link for anyone with similar performance problems and some how-to on various Honda models with EGR woes.

http://home.comcast.net/~em-engineering/T2T013.pdf

Thanks Again,

Stereowiz