Lexus Trouble

Lexus wont accelerate.  Just Revs.  First started
acting up months ago when i was at a red light the
car powered off while idling.  Started it right back
up and drove home.  Two weeks later I had gas
light on, i know i know its terrible, it was so late at
night and i had been driving so long, and the light
had just come on, so i drove the few blocks to my
house and figured i would get gas asap when i
drove again.  Actuality i let it sit for two weeks and
it just so happened it was the hottest two weeks of
summer, when i finally drove it it was slow to
accelerate so i went straight to gas station and
filled it up with the usual premium gas.  It started
accelerating fine and i was off on the freeway.  I
started smelling a burning smell,  not oil because i
know that smell.  It i hard to describe but it was
pungent like either gas or electrical but it went
away shortly after.   Car drove fine for 2 more
weeks and then one day it turned off when i got on
freeway about 6 minutes after starting it.  Code
said MAF sensor so replaced it and drove cool for
2 freeway trips 30 miles each way.  Then check
engine came back on and car would shut off and
on randomly again. The mechanic said it could be
air control valve or spark plugs or ignition coils so
we did a tune up and replaced all of them
including oil change.  Car never improved from
symptoms of low to no acceleration , the check
engine wouldnt read codes to the computer ( yes it
was correct diagnostic computer for my car).  
Mechanic then stopped charging me for labor and
put a fuel pump and filter but no luck.  He said its
time to sell.  He said it may either be ECU if not
that its the wiring harness, and if thats not it than
transmission is bad.  I said id think about it and
kept car parked in driveway just starting it to move
it up and down driveway, it still would take all my
foot on gas to get it to move.  I am very nice to my
car so i hated slamming gas pedal to move it.  
Finally i decided to just park it in garage but by
then my poor car wouldnt even start.  Jumping
wouldnt start it so as soon as i sprayed starter
fluid it started with jump.  Car wouldn't accelerate
at all it seemed, it wouldnt move forward.  I shifted
to L which i assume stands for lowest gear and it
moved forward all the way into garage, i barely
had to gas if any.  Ok sorry for the whole life story,
any advice is appreciated .  It has only 93,000
miles and is in good body condition.  If i cant fix it i
am wondering how low to sell for.