DOORSTOP

Change the front O2 sensor,It's under $80.00, called a air fuel ratio sensor, Usually a bad front sensor will cause this code.Also there are updates from Subaru on your computer, I would take the serial number and call your local dealer and see if there are any updates available.It shouldnt be to expensive to update it.

Problem solved I sent the customer to a local Subaru dealer and they re flashed the computer, (updated it) And so far so good.......I think I'm off the hook on this one

I wish I could find a brain to plug in and try I have heard about newer Subarus with brain problems and heard about trying to reprogram (flash) the brain...Still waiting to hear from a reply on that one.

No it will only act up when it wants to, Usually every day it will act up at least once

Start with a spray bottle of water. With the engine at idle spray the top of the engine mostly around the coil pack and wires, See if it skips and runs rough if it does replace the coil

Sorry about the caps Only codes are PO 303 & 304 Idle RPm is 700 and smooth unless it decides to stumble and then idle real rough kinda like a huge vacum leak All parts I use are OEM from Subaru Voltage at idle and on acceleration is 13.7 volts Thanks for the reply

Fuel pressure at idle was around 40 Lbs. and steady. Fuel filter is new and I removed the back of the air filter cover and gave a shot of Carb cleaner but no help still have same problem

Yes all parts I use are OEM from a Subaru dealer, I have been working on Subarus for 27 years and never been stumpted before,thanks for the thoughts

I Have A Customer With A 2002 Legacy Outback With 78k, The Check Engine Light Comes On With Codes For Number 3 & 4 Cylinders, The Car Also Stumbles And Wants To Stall Once And A While Coming To A Stop And At Times Will Stall. The Car Runs Great All The Time But Only Gives The Problem When Either Slowing To Stop Or At A Complete Stop, I Have Changed The Coil Pack, Plugs & Wires, Last Week I Tried To Change Both Air Flow Sensors (o2 Sensors) The Car Now Runs Much Better With More Power But Still Will Stumble Or Stall While Coming To A Stop...any One Ever See This Before, Any Help Would Be Greately Appreciated.