I first got gifted this car in 2022 (keep in mind it is pre-owned and has a salvage title), and at first all I had to do was to switch out the headlights because they were dim/not working. When switching these headlights, I found that they had drilled the headlights onto the bumper so it could stay stable with the body of the car. After finding several issues and fixing them, I am stumped with my latest car issue. When driving on the highway/freeway, the whole car would start to violently shake ONLY when stepping on the gas pedal, if I am not stepping on the gas pedal it would run like normal. I already tried balancing and tire rotation and it did not work. My first initial thought was that it had to had been an issue with the shocks, but I took it to Pep Boys and they had told me it was a CV axel issue. I ended up replacing all four shocks and CV axles around 2 years ago and have been keeping up with maintenance as well. It had a temporary fix on it for about a year or so before it started to shake again. Another issue that happens is that it won't shift gears correctly or it will take time to switch from parking to drive/reverse. This only happens when I begin to drive at the start of the day or when it has been idle for a couple of hours. Afterwards that is not an issue anymore for the time being, but the shaking still continues. I am thinking it a transmission issue (although I am hoping that's not the case). I am moving out soon and would like to fix this asap so I do not have any issues later down the line. The dashboard has a check engine light that keeps turning off and on constantly at random times. They had told me it was an electrical issue but I do not think that is the case. What do you guys recommend I should do? I was thinking checking both transmission and engine mounts first and start from there. I am fairly new in the car community so please have patience with me lol.