Mitsubishi Repair: 2000 Eclipse GT- Misfire in Pistons- P0300, P0302, P0303, rotor assembly, eclipse gt

Question
2000 Eclipse GT. Hey, I have had an ongoing issue. The check engine code keeps coming on with errors saying Misfire in Cylinder such and such, or a general Misfire altogether. Codes P0302, P0303, P0300. I have had this issue come up and get fixed at least 4 times, only to come up again.  This has been really expensive, and I probably should have sold the car long ago.  Symptoms: I start to feel an abnormal vibration on the gas pedal.  This vibration coincides with the engine running in and out badly, especially when ideling, in lower gears, and reverse.  Finally, I start to smell gas, and occasionally have gotten interesting looking exhaust, and the Check Engine light comes on.  Maintainance:  The dealer did a software upgrade for my cars PCM computer, which they claimed was causing it.  Runs okay for a while, happens again.  Next time I had the spark plugs and wires replaced, and I had the EGR valve cleaned. Runs okay for a while, happens again. Next, they replaced the failed/leaking valve cover gaskets, grommets, oil soaked ignition wires, worn distributor cap, and rotor assembly.  Currently, I have the P0300, general misfire code, and the dealer had to call Mitsubishi tech support, which suggests replacement of the distributor assembly. The part alone costs $800, with service we're talking about $1000.  I don't know what to do at this point.  I am thinking it is time to sell and get another car, but do you have any suggestions/revelations on what the overarching problem may be?  They are saying the fuel injectors are okay, and the error codes are ignition related.

Answer
Nick,
Per the codes you receive and the symptoms you've described it does sound like the problem is in the ignition system.  It's possible your timing itself is off, causing firing to be too advanced.  The PCM's response would be to stop a spark to prevent detention.  So if your mechanic has yet to check your timing or timing belt, have them do so.  Having a full timing belt and component replacement may run you around $800 itself.

But if you're on the fence of getting a new car, way the options of the cost of a new car compared to spending maybe $1000-$2000 to get your current car fixed.  
Good luck!