[kellio]

I have a 2000 Outback with manual transmission on which I've just replaced the head gaskets because of an overheating problem.
However, while the replacement has rectified the overheating issue, the engine now tends to miss badly but... it's intermittent.
For example, I can drive for half an hour without a problem on the highway but as soon as I slow down for traffic of have to stop and start again, the problem becomes evident in a way which could be described as "kangarooing"
where the engine will die momentarily or only run on 3 cylinders and or backfire through the exhaust.
I know the first thing to come to mind is incorrect cam timing but I was meticulous in setting it properly and have even tried retarding it 1 tooth which only made matters worse.
The timing belt and water pump were replaced by the previous owner not long before I bought the car so I didn't bother changing them again but I'm now wondering if that because I needed to compress the belt tensioner piston manually a couple of times when fitting and adjusting the belt, that it could have damaged it and be causing the belt to loosen sufficiently when hot to effect the timing of the cam closest to it.
Or...maybe the problem stems from something quite different...
Any ideas or suggestions will be appreciated.

 

[jbwood5]

I know it seems obvious, but have you replaced the plug wires and the plugs? Did you check the valve lash (SOHC)? Fuel filter replaced?

If you have covered the simple stuff, do a comparison between the two adjacent plugs to see if one has contamination on it.

Are you loosing any anti-freeze coolant? Any bubbles in the coolant reservoir?

If you don't mind me asking, what brand of headgasket did you use?

 

[kellio]

I know it seems obvious, but have you replaced the plug wires and the plugs? Did you check the valve lash (SOHC)? Fuel filter replaced?

If you have covered the simple stuff, do a comparison between the two adjacent plugs to see if one has contamination on it.

Are you loosing any anti-freeze coolant? Any bubbles in the coolant reservoir?

If you don't mind me asking, what brand of headgasket did you use?

Hi John and thanks for you suggestions, however the problem has now been rectified.
While all your suggestions were possibilities, the problem lay with the injector electric plug on number one cylinder being faulty. It's something which normally would never occur to me and I found it completely by accident when beginning to systematically check on every electrical connector.
Fortunately for me, they were the first ones I checked. :29: