P0303 p0031 p0660 p0705

My 03 Mazda Protege5 has 4 codes coming up. I'm wondering if they are all related or separate issues. The biggest is P0303 cylinder 3 misfire. Pulled the plug and it looked burnt around the bottom as well as a little charred above the nut. Replaced it but it still feels rough on 10 mile test drive. Will update whether or not check engine light comes back on tomorrow. Coil pack is connected to 2 and 3 so I didn't think that it was gone because only 3 was misfiring. Is this correct? Other codes are P0031 heated oxygen sensor - bank 1 sensor 1. I assume this is a symptom of the misfire as this is the o2 sensor in the exhaust manifold. Is that a reasonable assumption? The other two I am not sure about. P0705 is the Transmission Range Switch. Is this just a part I should replace or is there a way to diagnose a problem with it? The last is P0660 actuator circuit malfunction. I honestly don't even really understand this one. I have read a lot about it but nothing specific on how to fix it or even really what this code is telling me. Any help and/or guidance would be appreciated. Limited mechanic ability but I have learned by doing. So if it is not something that has gone wrong in my wife's or my car, I might not know about it. Thanks for any help.

P0660- replace the solenoid on top of the Intake manifold with the white plug going into it (cheap at JY but a crap-shoot as they commonly fail with age, around $100 at a dealer). Replace your ignition wires (~$40) and if they are old the coilpacks (~$60)and plugs($10) as well. I would get a new primary O2 if the heater is damaged in the current one. The P0705 can be tricky, you can try replacing the range switch. I am not too familiar with the ATX proteges.

Thanks for your advice. I replaced all 4 plugs and the one coil to the misfiring cylinder (the store only had 1 in stock) and the wires. This fixed everything except the o2 sensor so replaced that. Mechanic friend checked with his computer, everything is passing, no check engine light, just need to drive it to make sure nothing trips. Hopefully I won't have to spend the money on that solenoid. If I end up having to, there is a pick and pull near me, would it be worth pulling this part or should I just get a new one if I have to replace it? Same question for the TR switch.

I don't want to tell you to get the JY part because I can't guarantee it will work. Like I said it's a crap shoot. Most JY have a warranty for the part in case it is defective. That's what I would do personally but if you don't mind spending extra for new parts it's definitely the best bet as they will last much longer.