After Peter loss his memory, he used some sort of electricity charge to fight one of the thugs. BUT we know that Peter need to remember how the person made him feel in order to use the power.. So, what's going on?

I believe that Peter is now to the point that he just needs to feel the need or desire to use a power (that he has) to be able to use it.
Examples being... he should have been able to break the ropes holding his wrists behind his back but he didn't. He consentrated closing his eyes and next he phased through the ropes.
Peter saw himself use the "lightning or electric" ability so why not imagine he had more abilities.
The TX was used fighting off the two guys from the bosses sister. I think this was just reactionary because it needed to be done, just like regenerating.

My thought is that in the past 4 months Peter has been trained by someone, and then lost his memory. He is also wearing a necklace very similar to the one the Haitian wore last season, and if I am not mistaken, the Haitian's necklace is missing... hmmm.. The plot thickens.