My car stopped accelerating while on highway and wouldn't start after I shut it off

I have a 2005 Infiniti and have had
some problems. First off the engine
needed to be replaced so I bought a
used engine.  The engine ended up
being a bad engine it had timing
issues. So I bought another used
engine this time with a guarantee and
warranty from the place I bought it
from. In between this time the car was
parked on the street because I needed
to save $ for the labor. While on the
street some idiots syphered out my
gas and put diesel in my tank. So after
replacing the engine the car
overheated and the diesel blew the
fuel pump and spark plugs. Of course
they syphered out the diesel and put
regular gas in and replaced fuel pump
and plugs. About a week later I try to
leave work and the car wouldnt start.
Battery was fine and after about 45
minutes the car started up again and I
didn't have any further problems. This
was about a week and a half ago. This
past Friday I go to work and when I
leave I hop on the on ramp for the
highway and when I go to accelerate
the car just stops accelerating. I put
the pedal to the floor and nothing. The
dashboard lights flickered on and off
repeatedly, the check engine light, air
bags light, and battery light showed
up. I turned my yields on as I was
stuck on the highway and in minutes
they stopped. I shut the car off and
when i tried to restart it the car
wouldnt turn on. I had it towed to the
mechanic but haven't heard back yet
as they were just about to close when
my car was towed there.  I would
appreciate any professional feed back
on this and thank you in advance.