Could my coil be bad after only 40,000 miles?

I bought it new Aug 2011. I have
40,119 miles on it. Regular
maintenance and oil changes.  Recall
done.  2 days ago my wife is driving
on the feeway at 75 MPH on cruise.  
She pulled over because the car/
engine started shuttering. The car did
not shutter while pulling over.  She
turned the car off because it was
idling rough.  I told her to start the
car up a few minutes later while on
the phone.  The check engine light
and the electronic throttle control
lights were on.  She limped it to the
nearest gas station and waited for
me. On the way to the gas station it
would not accelerate without
shuttering violently.  I arrived a
couple of hours later, checked
everything and drove it at speed with
no issues.  The check engine light was
still on. I pulled the ground to reset
the computer.  The light went off.  
She drove it home 100+ miles. The
next day no issues.  This morning she
didn't make it out of the
neighborhood and it started again!  I
took it straight into the dealer who
told me it needs a tune up, new coil,
and gas system treatment!  That
makes no sense to me! 40,000 plugs
and coil?? My original tires aren't
even bald yet! Am I losing my mind
here.  Also the throttle felt "mushy/
spongy" when I drove it to the
dealership.  I got it up to highway
speeds by pumping the accelerator
pedal to get past the shakes. I am not
smart on these new tangled
automobiles.  Any help or advice will
be appreciated.