This all started a few months ago after the car (170k miles 2001 grand caravan) ran out of gas caused by a faulty gas gauge. Once it got started, there was a backfire and then it ran extremely rough. It kept running really hard for the next week, no limitations, just was slower at accelerating and louder.

We replaced the plugs and wires assuming that was the cause, all the plugs were shot, so they needed to be replaced anyways. Take it for a drive and then we get a misfire code from the second cylinder along with multiple misfire code. Being unable to do any repairs because of money, it ran this way for about a month. Again, nothing really bad about running, was just louder and slower. Check engine light would flash while accelerating because of the misfire.

Just replaced the ignition coil as a last ditch effort before ripping it apart to replace injectors. It worked. Kind of. Lights went away, runs a lot better but it's still a bit loud (could be caused by hole in muffler, not sure). Now just got P0420. Any suggestions? Could the cat could be toast from it running so hard for so long? (500+ miles a week for a month) It could just be a sensor but wanted to know what everyone else thought first. Thanks in advanced.

 

Clogged fuel filter, fuel pump damaged or going out.

 

Think so? Doesn't make much sense that it started running better once the ignition coil got replaced.

 

A flashing check engine light indicates a missfire severe enough to damage the cat. Yes, your cat could be toast.

 

Yeah, that's what I was assuming.