[TCGrove]

I also have a 1999 Chevy Blazer with 155,000. I began having that problem about a year ago. Generally in warmer weather. Always when starting the engine. I just got the P0300 code along with P0152 O2 Sensor Circuit High Voltage Bank 2 Sensor 1. I'm thinking these misfire are related to that. I'm going to pull the O2 Sensor and check it. I'll let you know the results. I've done the same things you have. New plugs, wires, rotor and cap, cleaned MAF sensor, gas filter, air filter, and new fuel pump a year ago.