My dad's got a 1994 Isuzu Trooper with right at 100k miles on it.  They are
getting ready to head out of town (my wife & I are as well) to the beach in
about a week, towing a travel trailer.  Hence the urgency of the request if
anyone has any suggestions.  Here's the story...

About a month ago, they had gone on a weekend trip (towing the trailer), and
on the way back, started having problems with the Trooper not acting right.
He said when he began to press in on the accelerator after having let off
the gas, it would tend to jump and buck and not want to run right.  It did
it several times, but he was able to get home without any major problems.
He was thinking perhaps it had something to do with running gas that has
ethanol in it (I forget the %, but such as is common for normal vehicles to
be able to run).

After getting home and running it solo trying to reproduce the problem, he
found that when he would stomp the accelerator, it would downshift to 2nd
gear and then have very little power.  He was unable to get it to reproduce
the "bucking" problem.

He took it to their normal mechanic, and he immediately reproduced the
problem.  Apparently their computer reader won't read a vehicle as old as
his, so he shorted something out to get it to give a code readout, which
confirmed his suspicion that it needed a Throttle Position Sensor.  After a
week of fighting to get the part in and installed, it continued to have the
problem.  It has also had an occasional and intermittent "check engine"
light.  The machanic managed to catch it in the act, and diagnosed it as
needing a MAP sensor.  After its installation, the problem continues.  The
mechanic tells him that it is now acting like it is trying to flood itself.
Not sure if the other symptoms have changed...

Sounds like they are about at their wits end as to what the problem could
be.  The Isuzu dealership would be the next logical choice, but they screwed
him over once already.  (Bought the vehicle there, they put on a new head
gasket before it was sold...broke off some bolts holding on the exhaust
stuff to the engine and basically fixed it enough to get it off the
lot...then told him he had bought it "as is" and they wouldn't do anything
about it).  So...the Isuzu place isn't a welcome option.

Any thoughts on what might be going on?  The backup tow vehicle is a 93
Trooper, with over150k...so obviously he would rather take the one that is
now having problems...  :-)

Thanks in advance,

Wesley