bad distributor cap would be first choice, next would be the rotor button in distributor.then the coil
a bad coil or plug to be safe change both
Trouble code P0300 means:Random/multiple cylinder misfire detected
Most common cause. Bad plug wires,distributor cap and rotor, Bad plugs. I would give it a GOOD tune-up
The most forward cylinder on the driver's side.
Drivers side, first one in front.
There is 1 per cylinder.
You will need to attach the wiring harness to the end of your 1984 Chevrolet Blazer ignition lock cylinder. Slide the cylinder into the cylinder slot. Secure the ignition lock cylinder with the retaining ring.
A bad transmission.
15 to 18mpg
Under the hood, on the driver's side of the firewall.
Random cylinder misfire
under the master cylinder.