Looses power under a load put in neutral give gas runs good

sounds like auto matic choke problem try a manual choke

If you have a carb its chock .If injection its fuel related filters regulator restrictions if fuel flow ect.

You have a bad valley pan gasket, not very expensive to fix at all, it is located under the intake manifold, happened to me and almost everyone I know that has this truck, goodluck

dirty throttle body, check air filter.

it sounds like the motor's tick over is far to slow when the car is put in gear if the tick over is say 750 rpm out of gear then it stalls when you put it in gear lift the tick over up to say 850 rpm the best way to set this up is have a friend sit in the car, warm the motor up, then get your friend to hold the foot brake hard on and put the car in gear, if it stalls bring the tick over up (in gear) till it dont stall,,,but hold the brakes hard on when your doing this,,,getting run over is not a nice thing to hapen to you and it wont make your day? you should feel a dit of a thump when you plop it into gear so hold the foot brake down when you do plop it in gear every time you do so, it saves the transmishion getting a thumping, all the things you have done to your car so far have only done it good, but why not change the oil and filter as well and know you have done the full monty on your car, and it wont need another service for another year or so?????

Check the MAF sensor. its the first sensor on the duct coming out of air cleaner good luck

Replace the throttle postioning sensor, and mass air flow sensor

try this, if the car wont start push the pedal all the way to the floor and hold it ther while you crank. It sounds like you are flooding the car some how. Pushing the pedal to the floor puts the car into clear flood mode and it shuts off the fuel flow. try and see just a suggestion

Sounds likes a Idle Air Control valve IAC problem.

gas pressure problem very dirty filter or gas pump when you have good idle and as soon you give gas the car dies no power that a low gas pressure hope its a fixya thanks pierre