alright guys my Girl just got a 2001 Blazer 4x4 with 134k miles. sense we got it the check engine light has been on it stays on constantly. When we take it on the highway 55MPH and above the check engine light flashes. The truck runs MINT there is no misfire, bucking, hesitation, or anything just the P0300 Code.
here's a list of the new parts we put on it.
New Coil,
New Plugs,
New cap and rotor,
New plug wires,
New ignition control module,
The MAF is good,
New Crank Position Sensor,
and ive replaces a bunch of old cracking vacuum lines. If you clear the codes it takes about 10 miles or so to turn it back on. But it always Flashes on the highway. Also the gas milage is good on it its not really ****ty. any help is greatly appreciated this code is getting frustrating cause its got a Rejection sticker on it and she has to drive it daily!

 

this might help

https://blazerforum.com/forum/diagno...4-5-6-a-35153/

 

I've gone through all that... I'm gonna pull the distributor tomorrow see how worn the gear is, after that I guess pay to hook it up to a smoke machine test for any leaks