I'm trying to figure out what I was told by a friend. 'To check the ecm ground'

It's an intermittent issue, so doesnt always happen but did once after a battery change and the engine light popped on

So what it was doing: turn on engine>get to going a little, usually in a parking lot>suddenly battery light is on and I have no gas(pushing pedal and it wont fo faster). >put into park and re-turn key> it goes fine or it repeats again.

Went to two different o rilies and they alternator is fine. But the battery was getting NASA so we assumed bad battery as the connections were tight. Replaced the battery and it's happened twice more, in the succession and hasn't happened again. I asked a friend to give a quick check of what he could, he double check all he could reach without taking pieces apart and said check the ecm ground. The engine light came on. Get that checked at an oreillys again. Get told and saw on screen "Internal control module incompatability"

it hasn't happened since that one time, 2 days after the battery was changed but I just really wanna make sure it's not gonna happen again. So really any advice besides take it to dealer/mechanic. I'm trying to learn to take care if it myself instead of paying an arm and a leg as I'm in school and tuition isnt cheap.

 

Sometimes a code will be stored in memory and that can provide some direction.
If the problem disappears when you turn the key off, it might require a code check before turning off the key.
Grant you some things are not always convenient, but it may be the one way to find out what is going on before it gets worse.
Intermittent problems can be very difficult to pin down since they usually get erased when the system runs fine a few times.
If there was any code found , please post it here and maybe we can offer some help.
Not sure if vehicle is going into "Limp Mode" or electronic throttle body is having a problem.which in some cases prevent much of any throttle response.