I haven't driven my truck for several months. It sat with clean oil and a low amount of gas. It won't start unless I put starting fluid in. I had the fuel filter replaced with a new one. I installed a new battery as well. I filled it with gas. When I get it to start and put it in drive, the engine would rev at 2400 RPM. If I apply the gas pedal too hard, the engine starts stalling. In neutral and park, the engine would rev normally. The truck runs well if I go easy on the gas pedal. What might be the problem?