Valve cover gasket replaced

So l had a small leak in my vehicle listed above. The leak was from a faulty valve cover gasket. Before l took it to the shop it was running fine mechanically. After picking it up the first day my check engine light halfway down the road started flashing, it would shake when idling at lights, and it was giving me resistance after l shifted gears and started to gas it. It felt like it was going to give out/cut off. I took it back to shop mechanic looked it over drove it did the same to him, he rechecked it replaced all the valve cover gaskets. I picked it up today on my lunch break and it drove fine. Much quieter than usual but l considered that to be a good thing. When l got off work tonight after 5-10 minutes down the road it started to give me trouble when l shifted again and would gas it after letting off the clutch. I don’t know much about cars but the only thing l know to compare it to is when you are first learning to drive a stick if you shift too early and hit the gas how it acts like it doesn’t want to go because you are not in the right gear for the speed you are going. My check engine light also started to flash. I’m at my wits end and heart broken that my older car that drove great before is going to have to go back into the shop again tomorrow for the third time this week. Does anyone know what it could be?