How do I fix my cruise and traction control?

Read the other threads re the PO420, as that may require replacing the front cat assy ($1200). Try clearing the codes and see which return. There's a chance you need an O2 sensor, as that's usually discrete from the 420. The misfire is because either your #3 plug is wet, loose, it's wire shorting to metal, or you have a bad coilpack. One at a time....Ern

Other issues? Your t-belt has aged out, so inspect carefully for cracks. Wheel bearings are common on all gens of Subies. You are also at moderate risk of replacing the CVT's valve body ($1k) or the entire trans ($3k used). Re[lace your crappy plat plugs with better iridium ones and chase that #3 misfire cause. There's a small chance #3 has dropped a valve seal, which would mean a rebuild of the right head (ouch!). Foresters also have many more idiosyncratic flaws that do NOT present in the domestic Legs/OBs, so good luck. Keep your fingers crossed on the CVT....