Rough idle-Misfire #2-#4 = Intake leak-exhaust-Timing?

[kevbot]

My wife brought my '97 outback limited home after work the other night- It sounded rough! It had been working just fine, except that morning I heard it make a -whirling- noise, like a squeaking pulley. When she brought it home it was making a very rough Idle-sounded like knocking or grinding at first-but was just generally loud. It must have been driving O.K. because she didn't seem to notice any thing was wrong. upon further inspection, it started up-rough- sound of open vacuum - clunking - and low grinding. I scanned the ECU and found; PO106 Pressure sensor circuit range/Performance problem - PO302 Misfire #2 - PO304 Misfire #4 - PO420 Catalytic operating below threshold - PO507 Idle control RPM to high. Although, some of those may be from before the problem occurred, as I have had a permanent CEL since I swapped engines. Anything you can think of will help. I might be pulling the motor to fix the rear seal which is *still* leaking.

Thanks

Kev-Bot

[98legacygt22]

check the knock sensor, if it's cracked that will make it misfire.