1996 gmc yukon giving p0300 code ive changed spark plugs and ignition rotor still misfiring checked for vacuum leaks and there was none

code p0300 refers to random/multiple cylinder/s ---misfire detected=== causes spark plug/s--HT lead/s--injector/s---ignition coil/s--low compression --wiring
Seeing as you have covered all the electrics, now concentrate on the injectors and fuel pressures
If you will do all injectors and the fuel pressure is where it is supposed to be ( pressure test) then you will have covered all bases
Low compression will be in the one cylinder only ans will remain in that cylinder regardless of injector or plug changes
I would leave that to the last resort as if it is random, it may be a loose valve seat insert that moves randomly causing a compression problem

Ive got the same issue with my 2007 Murano. I changed the plugs,ignition coils etc. But try replacing ur MAF (Mass Air Flow Sensor). Hope that helps fix ur problem.

START THE ENGINE AND LIFT THE IGNITION WIRE LISTEN FOR SPARKS.IF ONE OR MORE CYLINDERS DON'T CHANGE THE WAY IS RUNNING ,YOU GOT THE BAD CYLINDER. LOOK FOR BURN MARKS ON THE WIRE(BLUE/WHITE SPOT)IF SO REPLACE THE WIRE.SOME TIMES VALVE COVER LEAKING IN THE TUBE. REPLACE VALVE COVER GASKET,BLOW THE OIL OUT BEFORE REMOVE THE SPARK PLUGS.REMOVE THE SPARK PLUGS AND INSPECT THE ELECTRODE.GOOD ELECTRODE WILL BE WITH SHARP EDGE ,IF ROUND OR LIKE CONE REPLACE WITH DENSO OR NGK ORIGINAL EQUIPMENT . REMOVE THE DISTRIBUTOR CAP AND LOOK FOR OIL IN THE CAP. IF OIL INSIDE REPLACE DISTRIBUTOR. IF NO OIL INSPECT THE CAP AND ROTOR FOR THICK WHITE DEPOSIT OR ROTOR FOR BLACK BURN MARKS. REPLACE CAP AND ROTOR.IF EL.SYSTEM IS OK SPRAY CARB CLEANER ON INTAKE MANIFOLD AND LISTEN FOR RPM CHANGE.IF CHANGE THE RPM REPLACE MANIFOLD GASKET.

Are you check if have some fault code there? Misfinr g code could be P0300 or P0301, P0302... in order to cylinder.
A code P0300 may mean that one or more of the following has happened:
Faulty spark plugs or wiresFaulty coil (pack)Faulty oxygen sensor(s)Faulty fuel injector(s)Burned exhaust valveFaulty catalytic converter(s)Stuck/blocked EGR valve / passagesFaulty camshaft position sensorDefective computer

Possible SolutionsIf there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

Hope this helps.

P0300 Random/Multiple Cylinder Misfire Detected, the 304 is for cylinder number 4 any of these could be wrong If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors. Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open

Clean mass air flow sensor with a nonchlronated brake cleaner,install new air filter and check all vacuum lines for leaks then check for vacuum leak around or at intake manifold.Code P0140 is for mass air flow sensor code P0300 is a multiple misfire which more than likely is a vacuum leak possibly intake manifold gaskets leaking.

I have a 97 yukon with a rough idle, can you ntell me what you have found out.

Check all plugs and wires..If they are grounding out it will make it miss.Also check for vacuum leaks..Hope this helps you..Have a great day..

I’m happy to assist further over the phone at https://www.6ya.com/expert/joe_a3369546f8067589

P0131 - Heated Oxygen Sensor (HO2S) Circuit Low Voltage

P1133 - Heated Oxygen Sensor (HO2S) Insufficient Switching Bank 1 Sensor 1


Bank 1 Sensor 1
P0300 - Engine Misfire Detected

I would check for vacuum leaks, maybe intake or brake booster