Gas from the exhaust what could be the problem

it happens every time

I took my 96 Chevy Tahoe to get a replacement fly wheel installed for my transmission i was charged $412 for parts and labor, but 6 days later my car couldn't go into park. Does the mechanic I when to have to fix it at no extra charge?

Tahoe started fine ran around doing errands, came home shut it off went back out a day & half later and tahoe would not fire. Checked battery its ok, tried jumping it off still wont fire. What could be wrong.

I have replaced fuel pump, fuel filter, and throttle positioning sensor. It will set and run fine but the min you drop it in reverse it dies instintly. Even you try to give it gas. And only in reverse?

I drive a 97 two door tahoe 4x4 and I just recently changed my heater core out along with my thermostat spark plugs a wires this has all been within the past two weeks. When I changed the heater core I also flushed the radiator/heater core to get old coolant out after I did this the heat stopped working. Does anyone have any suggestions I what I can do to get my heat a defrost working before this season starts getting really cold?

I changed my fuel lines after one rusted into and changed fuel filter now not getting any gas through lines and i can hear the fuel pump running i have took the line apart and tried releasing the valve up on the motor and still nothing

can hear the fuel pump come on and has good fuel at injectors good fire on plugs just goes over and over without cranking