P0300 Misfire - 1996 Chevrolet K1500 Suburban 5.7L

[Trinfinity66]

I need some assistance. At this time I would randomnly get the p0300 error on my Suburban only on long drives of about 200 miles with an average speed of 70 mph. I would clear the code and not see the error again until I went on another long troad trip.

 

I recently changed out thefollowing items on my Suburban vecause they had not been done in about 75,000 miles:

• Spark Plugs (.60 Gap)
  
  • ACDelco Iridium - Spark Plug Part # 41-993
    

  [*]Plug Wires

   

  • BWD Select - Spark Plug Wire Set Part # CH7868
    

  [*]Distributor Cap

   

  • BWD - Distributor Cap Part # C282P
    

  [*]Distributor Rotor

   

  • BWD Select - Distributor Rotor Part # D236
    

   

   

 

After I replaced these items, I started to get the P0300 error on my wat to work (25 miles one way with an average speed of 60 mph). The vehicle idles great and runs smooth except for around 60 - 70 mph where I can feel a slight high speed miss.

 

Not really knowing the cause I went ahead and relaced the following items last night:

• Mass Air Flow Sensor
  
  • Cardone - Mass Air FLow Sensor Part # 74-8308
    

  [*]Oxygen Sensor (Passenger Side - Upstream)

   

  • Bosch - Oxygen Sesnor Part # 15703
    

   

   

 

This however, did not fix my problem. The screen in the MAFS was dirty and and the O₂ sensor had 2 of the 6 openings plugged.

 

Again the vehicle idles and runs great except for that speed range. Here is the Freeze Frame Data taken this morning:

 

Fuel Sys 1 CL

Fuel Sys 2 CL

Calc Load (%) 18.04

ECT (*F) 183

STFT B1 (%) 5.47

LIFT B1 (%) -2.34

STFT B2 (%) 5.47

LIFT B2 (%) -2.34

MAP (inHg) 12.99

Eng RPM 1,931

Veh Speed (mph) 64

MAF (lb/min) 4.50

 

Of course along with thise numbers comes the error code of P0300.

 

I would appreicate any and all help here.

Thank you

[gmtech4]

you spent alot of money guessing and now you are here ,,,

 

welcome but as you'll find im a big advocate FOR NOT THROWING parts at a problem,

 

now you'll have to spend more money to have the intake done which MAY be the problem,or the injectors or or or etc etc

 

good luck and welcome again ,sorry i get mad for wasted money that couldve paid for a diagnoses that holds the shop accountable not you