When you push the gas pedal does the engine RPM rise but the vehicle doesn't move? If so I think the problem is more likely a transmission problem. Check the fluid level, engine running check the oil level on the transmission dipstick.
Have you had the transmission oil changed in the past?
If it is an ignition misfire or spark plugs braking down under load with the transmission in neutral does the engine idle smoothly?
I have seen bad engine mounts tear the air induction rubber boot and cause the car to have a drivability problem as you pull away from a stop.