1998 Chevy Blazer when I press the gas pedal. It seems lik

Hi. WHen I first start driving my Blazer. It seems like it cuts out a little bit. Kind of hesitates. And even after I start going 60-70 MPH. It seems like it is missing.I took it to a mechanic and he said maybe it was just the gas. He told me to add some gas treatment to the gas. Something called B-12.
It was better for a week or so but now it is starting the same thing again.

I was reading on another website that it sounds like it could be a blown out pressure regulator or stuck jpoppet valve pinties. Causing mis-fueling. Stating that this was a common problem for s-10's with high mileage. Also stated that if some of the plugs were wet with gasoline when they were pulled. This would be an easy tipoff. Suggested to put a MPI conversion kit in instead of replacing injectors and regulators. What does this sound like to you?

I am a female and I do not want to get ripped off for parts that I do not need. Please help>>>thank you so much. Betty