1980 DL wagon
219,000
Original engine and auto transmission

My 80 DL wagon recently started running extremely rough. So rough in fact, that in cannot be driven more than 5 mph. Sounds and feels like it's running on 2 or 3 cylinders. You can increase the rpm's, but still has a steady severe miss. It ran like this one morning a few months ago, but cleared itself up after a few miles and has run fine up until a few days ago.
I've already gone through the ignition system and everything checks out fine.
I'm not so familiar with the fuel system however. I was thinking about donating the car to charity, but my son's car went into the crapper recently and I would like to get this running again without spending much.

I'm also thinking about buying another wagon in the next few months, and would like your opinions on what which models to look for and which to stay away from.
Which of the RWD turbo wagons are worth looking into... 740's, 760's, 940's, 960's or maybe even a 245 turbo. How is the powerplant and transmission in the 900 series turbos different from the 700 series turbos. Which is more reliable?

You folks are the best.
Thanks
Derek