Mitsubishi Repair: 96 Mirage Pressure Problem, mitsubishi mirage, highway speeds

Question
Hi.  I have a 96 Mitsubishi Mirage LS Coupe, 1.5L Automatic.  Initially, one of the valves got too tight, so I took it to the dealership to be fixed.  Ever since then, it's had problems accelerating.  If I give it too much gas, it sputters and tries to die.  I had the catalytic converter replaced after making small repairs (02 sensor, plug wires, and fuses).  The up side to all this is that when it finally gets to highway speeds, it only has a little trouble on steeper hills.  I also find it easier if I drop into low gear, then 2nd, and finally back into drive (just as you would with a manual transmission).  The check engine light used to come on infrequently, but it wouldn't throw any codes.  Now its pretty rare for the CE light to come on, likely because catalytic converter was removed (since it was replaced, it was damaged beyond use).
The last shop I had it in to suggested that the distributor needed to be replaced, however the parts dealer suggested that the pressure sensor ought to be checked first.  I'd like an unbiased suggestion for a change.  I've compared the wiring configuration for the distributor against another Mirage, and its set up right.

(If you can't tell, I know little about cars - I'm a computer expert)  :p

Answer
Shane,
I don't quite understand what you mean when you said "one of the valves got too tight".  

Either way, it is a good idea to have your pressure sensor checked.  I'm guessing the parts dealer is referring to the pressure sensor that is part of your mass air filter sensor.  That pressure sensor is responsible for telling the car's computer the amount of air and even the barometric pressure of the outside air entering your engine.  If the sensor is sending the wrong signal, the ECU may allow too much or too little fuel.  That can cause stalling at low and idle speeds.  That usually is not a problem at highway speeds because your car is at WOT (wide-open throttle) and the ECU simply sends the most amount of fuel possible in that situation.

I'd advise having a couple mechanics inspect both the distributor and pressure sensors.  If the problem is with the distributor, verify if it's the distribor cap or the actual distributor.  The actual distributor is much more expensive.
Good luck!