A little over a year ago, there was an acceleration/hesitation/stumbling issue with my wife’s ‘99 Blazer. Well, this is what has been changed out since from beginning to end: plugs, wires, distributor cap, MAF sensor, fuel filter, air filter, thermostat, coolant temp sensor, and finally, the ignition coil. I had completed all necessary oil changes at intervals, cleaned throttle body intake, flushed and refilled coolant. This has stumped me for some time and I have taken it to two different mechanics and they have told me to do all that you see above after doing diagnostics with no codes and pressure in all lines. Finally, it was my local auto parts shop guy that recommended me to stop using gas with Ethanol and use Berryman’s B-12 Chemtool Fuel Injector Cleaner for two weeks. Well, I must say that this stuff is magic in a bottle. I have been through Lucas, STP, Chevron, and all the names in the Walmart’s as a fuel additive. The first day, letting the gas run down in the tank, refilling with non Ethanol high test and using one bottle of the Berryman’s, and the car no longer has the issue. Thank you to not only all the people that recommend non Ethanol gas, but the clerk who recommended this product. The very first day running the car was noticeably different and now a few days later, my wife says there still is no problem. Looks like I would recommend this to everyone reading.