I recently bought a 2003 blazer xtreme.
has a number of issues I had to correct... One of many was fuel pump and random misfire... Replaced pump and did a complete tune up... New distributor plugs and wires... Check engine light is no longer on however when I get to 70mph it comes on and flashes... Once I slow to 60 it turns off... I've been searching online for days on forums... Have found several possibilities but all point to a misfire which supposedly has been corrected since the cel is not coming on until 70mph...
Any help would be greatly appreciated

 

Sounds like you are having a high rpm misfire condition. Perhaps a bad coil?

 

Possibly... I can't get the codes pulled because it only does it at speed.. Might go buy an obd2 reader and see if I can pull the code myself while I'm driving lol

 

If a code is setting, it is stored in the pcm memory. It does not need to have the cel illuminated to be able to be read.