The car drives great for a seemingly random amount of time; sometimes 20 minutes, sometimes 60+.
Once it`s been driven a while, the problem starts small. There is a slight loss of power when accelerating. If I had to attach a number to it, I`d say it`s in the 5% ballpark. You likely wouldn`t notice it at all if you weren`t used to driving it. It`s the prelude to the following:
After the tiny power loss described above, a minute or two pass, and the loss becomes more significant. It starts to hesitate when accelerating. Sometimes it will come back to life for a few seconds, but not always.
What DOES always happen: Eventually, the check engine light will turn on. Once the check engine light is illuminated, all bets are off, and you may as well pull over and turn it off. Acceleration slows to a *crawl*, sometimes taking a full 15 - 20 seconds to get up to 35MPH. It refuses to go any faster. The car will respond to pressing the accelerator (you can feel it heave), but it has the opposite effect. Pressing it lightly will keep it at it`s current speed (up to 35ish), but the harder you press, the car just slows down.
Once it`s had enough, the car will sputter to a halt. You can start it again, but it will die immediately.
Here`s the odd part: Letting the car sit will roll the problem back (depending on how long you let it sit). Generally, you can get it to run after 20 minutes or so, but you`ll be right in the middle of the problem, and your destination had better be close by. Let it sit for a few hours or so, and the problem is gone... for a while.
Everyone I tell this to says "catalytic converter." My mechanic disagrees because of the random timing of the problem. He seems to think it`s electrical. I`m no mechanic, but the nature of the problem says to me that it`s an issue of something getting too hot to function properly.
I don`t know whether to go through with expensive diagnostics or scrap the car. Any thoughts?