2002 PT Cruiser Transmission Issues?

I just purchased a 2002 PT Cruiser 4D with 107k
miles on it. Was told it sat for 5 years. I was also
told to change fuel due to the time it sat. I drove it
for a week worked great. Had some failed starts but
I figured it was due to cold weather. Now I am
unable to drive one block or go past 15 mph
without it revving up and not moving. Had to drive
reverse to get back home.  Transmission oil
appeared low added till full. Oil low added 5 gal.
Had some cranking or clicking  noise when driving.
Noise isn’t terribly bad but enough to notice. Check
engine light on but haven’t been able to check yet. I
bought car on payments ‘as is’ from a private seller
that mentioned car was given to them and they
know little about cars, yet work at an auto parts
store?! We signed an agreement that buyer is
responsible for payments even if any mechanical
errors. This was my first mistake. Long story short
my last car had transmission issues and the cost
was too high for what I could afford. So I got this
Chrysler and now this appears to possibly have
same issues. I have little cash to afford repairs.  
Help appreciated. Thanks.