Recently my girlfriend ran her car dry on oil. Since money was very tight at the time, I decided to limit myself to $1000 for a "band aid" car. Through some good fortune, we were the first caller for an '89 740 GL wagon in Memphis and bought the thing for $850. It has 303k miles with a mid-life engine replacement, but the body was very straight except for some deer damage to the left front. I'm assuming the engine replacement was a b230f (?), but I haven't checked the block yet. I think she's fallen in love with the car and would like to extend its homelife in her driveway beyond something for just a few months. Recently though, it's been acting up, and I live 200 miles away with a startup business that's been keeping me too busy to visit the car in person. Here's the way she describes the problem:

"First, it doesn't want to stay running when I first start it . . . unless I immediately put it in gear and give it gas, it wants to (and does, sometimes) die. When I take my foot off the accelerator, it does little 'putt putt putt' backfires. When I brake quickly, the RPMs fluctuate wildly . . . it really wants to die. It didn't die at a stop sign today but it came close a couple of times. One other thing - and it may be unrelated - it seems like the temp gauge always fluctuates when it idles rough . . . but sometimes the temp gauge fluctuates when it is running smoothly. I'll try to watch it to see if there is some sort of pattern."

The previous owner said that occasionally we would have to replace a sensor (the oxygen sensor perhaps?). Does this make any sense? If so, what's the easiest way to check such a thing? Can she drive to a corporate auto parts house like O'Reillys or Advance to have it tested? I've been reading a little about diagnostic codes...but what is required to access them? A separate device, or simply shorting between a couple terminals in a fuse box and reading the Check Engine light sequence?

Thanks in advance...Jeff