I have a 99 blazer that boggs severely @ 40 mph I have scanned the computer and no codes it really doesn't have a specific occurance, it does it with or without the a/c and no matter what the traffic situation. I have also had a weird idling problem again no codes I use gas from CFM generally and have had no problems but for the last couple of monthsit acts up every couple of weeks where it starts but then you almost have tokeep it running I have check the vaccum lines and made sure that they werethe way they should be. From whatI have researchedand been told it is probably the converter. Wouldn't it throw a code though?

 

Converter, as in torque converter in the tranny?
If the converter was going out it would happen in all gears at the same rpms.

Sounds more like a fuel related issue. When was the last time you changed your fuel filter, and get your fuel pressure tested.

How many miles and has it ever had a tune up?
I like to start with the basics before condemming expensive to replace parts.