Q: What does ECP and ECM mean and is it bad?

Hello. I suspect you mean EPC (not ECP), which stands for electronic pedal control or electronic "gas pedal linkage". There is no longer a physical cable, wire or lever between the gas pedal, and the throttle body on the engine which regulates desired power.

The "gas pedal" has an electronic actuator and wiring that connects it to the electronic throttle position actuator on the throttle. These components are "paired", coded to each other in software, and have some level of awareness of each others precise characteristics.

If you replace one or the other, they must be "paired" to each other. Most likely the throttle position sensor is failing, and the software is detecting this. There should be problem codes indicating which component is failing (Check Engine light). ECM simply means "engine computer module", the electronics that manage your fuel injection, ignition timing, and if you have an automatic transmission that regulates how the transmission should shift based on gas pedal activity. Virtually all cars and trucks built today have at least one ECM. I would recommend having a Check Engine Light inspection completed by a mobile, professional mechanic, such as one from YourMechanic, to diagnose this problem, get an accurate assessment of damage, and estimate for repairs.