My truck runs great while parked but when i try to drive it has no power with a load

check that the wires are in the correct places. (google search the correct firing order/wire locations)
Check spark plug gap.

Trouble shooting a misfire, Code P0300, P0301 ... - YouTube

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www.youtube.com/watch?v=G_grIaTgdRI
Oct 26, 2013 - Uploaded by Robert DIY For the new play by play misfire video click here: ... Trouble shooting a misfire, Code P0300, P0301, P0302, P0303, P0304, P0305, P0306, ...

If you can make the injector click without cranking the engine, the injector ground circuit is bad, probably the computer.
If the injector only clicks when cranking, the ground circuit is working right, so the problem is with the injector drive circuit. There should be a fuse for the injectors in the power distribution box by the battery. Have you checked for that? Also check for power to the fuse with key on. Use a testlight or voltmeter to check for power.

check your Park/neutral position switch (automatic transmission), it may need cleaning or repacement
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it may need cleaning

Did you double check the plugs? If there's a bad one (I know they're new) It'll run bad under a load

Mine was doing the exact same thing. You will need to crank it up, raise the hood, take the oil cap off, place your hand over the hole, and if it sucks on your hand you have a blowed intake gasket.

IN your distributer under the rotor is a magnet and a pickup coil (the magnet is known as a pole piece) check your pickup coil for corrsion (green in color) and the module and also check pole piece for cracks in the magnet where the rivets hold it together. sometimes oil wicks up around the distributer shaft because of housing wear or the pieces just wear out over time.

DO A LITTLE TUNE UP.CHANGE SPARK PLUGS.CHANGE FUEL FILTER.CLEAN FUEL INJECTORS.FILL FUEL TANK UP.AND ADD A BOTTLE OF FUEL INJECTOR CLEANER IN FUEL TANK.WHEN YOU DRIVE CAR AROUND.THE INJECTOR CLEANER WILL CLEAN OUT FUEL INJECTORS.IF CAR STILL RUN ROUGH IN DRIVE.YOU COULD HAVE INTAKE LEAK.

Put an injector noid light at the injector plug terminals to see if your getting a signal from the PCM(computer).If not try to find a computer from the same vehicle that works and swap it into yours to check.A PCM swap will take about 15minutes.

SOUND LIKE ENGINE IS FLOODING. FUEL INJECTORS IS LEAKING FUEL WITH ENGINE OFF.TRY FILLING GAS TANK UP.AND PUT A BOTTLE OF FUEL INJECTION CLEANER IN GAS TANK DRIVE AROUND A LITTLE SO THE CLEANER CAN CLEAN INJECTORS.