01 with CEL

[trivownr]

My 01 has about 180k, I bought it a year and a half ago with 152k. It has had the CEL on the whole time I've owned it. It had codes for front bank cat, knock sensor, and cyl 4 misfire.

I replaced the knock sensor and that code is gone. I replaced both O2 sensors in the hope that would fix the front bank code--it didn't.

I replaced the coil, plug wires, and plugs and the cyl 4 misfire went away, temporarily. Driving to work one day the CEL started flashing and I lost power. I was able to get it to a repair shop that specializes in Japanese cars and after two days they discovered my new coil had gone bad. When they replaced the coil, they told me that the #4 plug wire was bad, so I replaced the plug wires, again.

Now, a couple of months later, when the car idles or when it's running at a constant "high RPM" (4500 or above) the CEL flashes. If I drop down a gear and get it in the 2 to 3 thousand RPM range or raise the RPMs when I'm at a stop light, then the flashing stops.

Had the codes read again and it still reads front bank and cyl 4 misfire. Any ideas?