Tachometer fluctuations

I took it to a shop, they replaced the spark plugs, wires and dist. Cap. Do you think they installed it incorrectly?

Here is the full story. Bought it a year ago. Not even a month later it just died randomly no codes no warning signs. Toyota dealership replaced the coolant temperature sensor. Here is where it gets fuzzy. I believe this is where it started this flickering issue, though not as bad, it would still drive. When the problem showed itself it would be very quickly then back to normal. Took it to a shop, they replaced the spark plugs, plug wires, distributor cap, replaced the fuel filter and flushed the fuel lines. The problem is seemingly worse, less dependable almost everytime I get it to stall. I also have a video of the whole incident that I could show. Maybe attach through the email?