Multiple clyinders misfiring

I was driving on the interstate all if a sudden she acted
like she wasn't getting power/fuel. When I'd push on
the gas pedal the car acted like it was going to stall out  
of shut off. So I drifted /coasted to the next exit. After
that she wouldn't start. You can hear it cranking but
she wasn't able to kick over. So I had it towed home.
Since then I have put 1700$ into trying to get her
running again.
I have replaced the battery, starter, alternator, fuel
injectors, fuel pump, fuel filter, air filter, plugs & wires,
oil change, new heads & gasket, new timing chain &
gasket, and a distributor cap.
I had it towed to a mechanic. He is did get it to start &
stay running ; but it run like shit. When you went up a
hill or set at a light, it wanted to stale out. It took me an
HR & ½ to get her home from the Mechanic's shop.
Normally that is a 30 min drive. It idles like it's about
the quit; if ur at a stop light I had to put it in neutral so
it wouldn't stale out. There only certain things that will
start a car. I've damn near replaced all of it. I can't
afford to keep buying all these parts. Will someone
PLZ help me.