I hope i'm posting this correctly, I looked and I didn't see a post that would answer my problem. I'm new to this forum and to posting in forums in general.

I have a 1996 850 base with approximately 145,000 miles on it. The odometer stopped working around 136,000, so I'm guessing and rounding up a little. I bought the car used about 2 years ago. I have had little work done to it, but it hasn't needed much. A couple of vacuum lines replaced, a few things to fix the air-conditioning, (a new drier/receiver, one new hose and an evacuation/charging), one strut mount replaced, the bushings replaced on the fuel tank (under warranty), new lines put on the top of the fuel tank, new battery and a new fuel filter. The car ran great. I loved it. The interior is in great shape and the exterior is pretty good as well, all it needs is just one of the moulding pieces replaced on the drivers side roof.

My problem started about 1 week ago. I was coming back from an appointment, it was hot outside and I had my air conditioning on. I was using my cruise, and the car had to downshift to make it up a hill, all of the sudden, my car started acting running rough and the CEL popped on and started flashing. My CEL pops on occasionally, due to the rear o2 sensor going bad, but it has never flashed before. I stopped into the local Autozone and had them read my codes. P0302 cylinder 2 misfire, p0304 cylinder 4 misfire, and p1310 misfire from at least 1 cylinder TWC damage. The guys at the store said I probably need a tune up.

I got the tune up kit for a non-turbo 850 from FCP and put that on. As I was changing the spark plugs, I noticed that the #2 cylinder was a yellow colour inside(?), all of the rest were silver. The #2 and #4 plugs were dirtier than the rest, but nothing too out of the ordinary I thought. After I replaced everything and got it put back together, I started it up and it still idled rough and the CEL was still blinking. I took it to the Autozone and they checked it again and said it was still throwing the P0304 code. The car's running does smooth out when I get over 35 mph. If it were the plugs or wires, the tune up would have fixed the problem, and if it were fuel related, (as I had thought also), it would affect other cylinders as well, am I thinking correctly on this?

About a week before my car started acting up, I changed the oil. A week before I changed the oil, the level was down a little and I put a can of Seafoam into the crankcase. Could that have cleaned things too much and messed something up, as my brother told me was likely? I am on disability and therefore, on a fixed income. I do not have much in the way of savings nor in the surplus at the end of the month. I need a car, the public transportation where I live is negligible, and I cannot walk far. I do not drive very much in a week, probably no more than 150 miles. Any thoughts on what I could try to fix it as a simple, inexpensive solution? What are my options? I have tried to be as thorough as possible in my explanation, if more information is needed, please let me know.

Thank you in advance for your assistance.

 

What all was changed with the tune up kit?

You may want to do/have a compression test. That will tell you if you have a worn piston or leaky valve or something.
Compression Test - Volvo S70 GLT, 1998

 

I changed everything that came with it, the spark plugs, ignition wires, cap, rotor, and the air filter. I checked and rechecked to make sure everything was where it's supposed to be. If I do find something wrong with the compression test, what would my options be? Or is it too early to tell? Like, if I did have a worn piston or a leaky valve, what would fixing those things entail?

 

Eeeek! I'm from the school of, lets cross that bridge if it joins our road.