Knom

I have an 01 ES300 with 107k miles.

The checked engine light came on, then freaked me out by flashing so I figured something really bad must be happening there. I'm not that mechanically inclined but I can google pretty well.

My mechanic said the codes were P0300..0301...0302 all the way to 0306. I researched and found this means it's a misfire. I had all of the ignition coils and spark plugs changed. The codes erased, it drove ok for about ten minutes.

The CEL came back. I waited until my friend came to flush my transmission fluid and talked him into looking at it. The scanner gave the codes P0300, P0303, and P0305. He made sure everything was connected and noticed oil was leaking into one of the cylinders (I think that's what it's called). To fix this he cleaned it out and replaced the valve cover gasket then cleared the codes.

The car still has an attitude. It sputters when at low speed, at a red light the RPMs go up and down and car shakes. I don't know if it's related but I seem to lose pressure in the brakes as well but only when the car first begins to start shaking and sputtering. The CEL only flashes at low speeds, the car only have these issues at low speed.

At highway speeds the CEL doesn't flash, actually it stops flashing at around 35mph. My research has led me to believe it may be a vacuum leak? Would this cause a P0300 code though? I'm trying to have as much info as I can before having the mechanic look at it again.

mmatheny

I'd check the vacuum hose going to the brake vacuum booster - that sounds like the culprit from all the evidence.