Oldsmobile/Buick Repair: 1999 Buick LeSabre Sputters Up Hill, mass airflow sensor, altitude changes

Question
Hi Billy:

We are having a weird problem (been going on for about a year or so) with our LeSabre.  In the desert, one has to travel through mountain passes quite frequently on the highways and that is when the sputtering of the engine is at its worst.  My husband went to Vegas and said it was so bad he had to put it in 3rd gear and just "gun it" to get up the hills this time.  We've tried the advice of putting in high grade gas but it doesn't seem to do it.  Could it be the fuel injector? Transmission? Even something like a regulator or computer malfunction?  We are just stumped and have already off-loaded $1,000 on new brakes for the front and rear in the last month (only 79,000 miles on it) so as you can see, we're a little gun shy about taking it to the dealer for an expert opinion of $200 to tell us they can't figure out the problem.
Thanks a million for your help. :)
Jeannie

Answer
HI JEANIE, I DREAM OF JEANIE,I REALLY DO MY WIFE,S NAME IS JEANIE ALSO.GOTTA LOVE THOSE DEALERS JEANIE.WELL DESERT REALLY DOESEN,T CONCERN ME .HOWEVER THE MOUNTAINS COULD BE A PROBLEM.ALTITUDE EFFECTS THE EFFICIENCY OF SENSORS.FUEL GRADE IS ALSO EFFECTED SO THE QUESTION I GUESS IS HOW HIGH ARE THESE MOUNTAINS,YOUR COMPUTER CAN COMPANSATE FOR SOME ALTITUDE CHANGES BUT NOT ALL.I WOULD HAVE TO SAY THAT YOU NEED A MASS AIRFLOW SENSOR FOR HIGHER ALTITUDES AND ALSO OCTANE BOOSTER.IN EVERY TANK.YOU CAN USE REG UNLEADED GAS JUST WITH THE BOOSTER.AND ONE MORE THING IF YOU DON,T REMEMBER WHEN YOU REPLACED YOUR AIRFILTER AND FUEL FILTER THIS WILL BE A GOOD TIME.BE SURE WHEN YOU GO TO THE MOUNTAINS YOU HAVE A FULL TANK OF GAS.IF YOU HAVE A STRAW IN A GLASS AND ON LEVEL SURFACE GLASS IS HALF FULL YOU CAN DRINK IT NO PROB.BUT TIP THAT GLASS 45 DEGREES AND YOU CANNOT.SAME EFFECT WITH FUEL TANK.HOPE THIS HELPS IF NOT WRITE BACK I WILL HELP PLEASE VOTE FOR ME TY BILLYMAC