02 4 cylinder 5spd unsteady idle and unsteady/surging light to moderate throttle

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Hello
I have a 02 Subaru Forester with a 4 cylinder engine and 5speed transmission. I’ve had an issue that started about 1.5 months ago and I’ve been trying to fix it since then. I have time, some basic metric tools and a shop with a wood stove. Problem started as a very uneven idle in the cold MT mornings where the engine would sound as though it was going to stall then surge up to a high idle then back down to where it sounded as though it was going to stall again repetitively. However the engine has not yet quit while idling. This problem rapidly worsened to where the engine would also instantly lose most power upon light to moderate acceleration at lower rpms. Then get the power back then lose it again until it got up to about 3000 rpm or a steady highway speed in 5 gear. It would jerk and surge so bad that sometimes I could smell my clutch a bit as it was taking a beating. It threw a cylinder misfire code before replacing spark plugs which removed that code but didn’t solve the problem. The next time the CEL came on the parts store scanner read a code saying something along the line of ‘fuel too rich on passenger side cylinders’. So far I have cleaned the throttle body, replaced valve cover seals and spark plug housing seals, replaced spark plugs, replaced spark plug wires, replaced fuel filter and finally yesterday I replaced injectors which got rid of the CEL. After changing injectors and first start up, it idled really bouncy like an injector was not getting any electricity. After about 5 mns of idle and a short drive down the highway and back the car quieted down and began running perfectly. I proceeded to drive it about 20 miles without any issues thinking that the new injectors had solve the issue! This evening it is idling uneven again and surging at light to moderate acceleration just like before. When changing spark plugs and later injectors the spark plug and injector on the passenger side seemed to be dirtier than the drivers side. Any ideas? I’ve invested a bunch of time and parts into this and would of course love to solve the problem without using a dealership but I don’t have a scanner of my own and am not good with diagnostics especially electrical. Coil pack? Fuel pump? Sensor? Electrical?
 

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