My 2004 Explorer will not accelerate, only idles. Disconnected the battery to clean the terminals. Charged the battery on 6amps High for two hours. Started fine but will not accelerate from idle.

Alternator possibly.

On some vehicles, the computer has to "learn" how to run efficiently after the battery has been disconnected for a period of time. I had an 04 Cadillac that would not idle either after the battery was disconnected for several hours. I tried everything to get it to idle right, resetting the computer, etc. Once I actually drove it around the block it started running correctly after about 1/8 mile. I could not get it to "learn" until I actually drove it, letting it run in park for almost two hours was not enough, it had to go through the process of actually driving to get everything back to normal.

Check for any disconnected hoses that may be causing a vacuum leak resulting in a high idle. Make sure coolant level in radiator is not low which can also attribute to a high idle.

It sounds very battery related like the battery is on the way out, but start looking at the easy things first.

Clean the top of the battery and the terminals with a solution of hot water mixed with a tablespoon of bicarbonate of soda.
This will neutralize the acid.

Rinse with clean water and dry the area.

If your radio has a security code obtain this first before proceeding with the next steps.

Remove the negative battery terminal (black) and thoroughly clean the battery post with sandpaper or wire brush, and then the terminal itself.

Repeat the same for the positive terminal (red).

Be careful not to join a circuit between the two terminals with a metal object.
NEVER test a battery's level of charge by jumping the terminals together with a screwdriver or similar to see if it sparks, it will mostly like ignite the Hydrogen gas in the battery and explode.

Check the electrolyte levels in the battery if this can be checked, and top up with distilled water if necessary.

Charge the battery overnight with a borrowed or bought battery charger.

If you have a voltmeter check the voltage with the battery fully charged and disconnected from the battery charger, it should be at least 12 volts DC.

Start the car and check the voltage again, it should be greater than 12 volts, usually around 13 volts DC or a little higher.

If the issue still occurs after this take the car to an auto shop that has a decent battery analysis machine, and they will also be able to test if the alternator is outputting the correct voltage and the regulator.

I had this same problem. Worked on it for two weeks. Checked for vacuum leaks and checked IAC, MAP and EGR flow sensors. All good. Turns out the PCM was corrupted. Disconnected battery for a half hour (cleaned battery while at it). PCM reset after battery reconnected and idle is now normal.

Pull the connections on the battery and leave it disconnected for 10 minutes. Reconnect and test.

Give it a full tune up and clean the throttle body.

battery terminals?? cable disconnected on the positive terminal,one of the big fuses near the battery has a dirty connection??

Ford 2004 6.0, Driving down road seams like when it starts warming up it starts Missing or accelerating,jerking,as long as you keep the acceleration it seems to work as soon as you level it out it starts missing,even dies at stoping sometimes...Changed fuel filter, put fuel additive in tank still missing,HELP

Have the Idle Control Solenoid Valve cleaned up.

Or it might be defective. See steps below to check...

1. Disconnect idle control solenoid valve electrical connector.
2. Disconnect upper hose to solenoid valve from manifold and apply vacuum to hose. Valve should hold vacuum.
3. Continue applying vacuum to hose and briefly energize valve by connecting battery positive terminal to the black/yellow wire terminal and negative battery terminal to the green/black wire terminal. Valve should not hold vacuum when energized.
4. If idle control solenoid valve fails to perform as outlined, valve is defective.