slow idle on my 1999 5.3

[Steve Ks]

Recently my 1999 chevy z71 K1500 extended cab (70,000 mi) has been idling rough after it warms up. The idle speed slows down to about 400 rpms and it acts like it wants to die. It will catch itself and speed up but quickly slows back down to around 400 rpm and acts like it has a intermitent miss. The only code I found on the OBD is 0300 ramdom misfire on multiple cylinders? It runs fine at higher RPms and runs down the road just fine. I have changed the air and fuel filter.

Any suggestions would be greatly appreciated.

[Steve Ks]

anybody have any ideas to try on this problem?

[Air Biscuit]

Recently my 1999 chevy z71 K1500 extended cab (70,000 mi) has been idling rough after it warms up.  The idle speed slows down to about 400 rpms and it acts like it wants to die.  It will catch itself and speed up but quickly slows back down to around 400 rpm and acts like it has a intermitent miss.  The only code I found on the OBD is 0300 ramdom misfire on multiple cylinders?  It runs fine at higher RPms and runs down the road just fine.  I have changed the air and fuel filter.

Any suggestions would be greatly appreciated.

 

<{POST_SNAPBACK}>

 

 

 

Have you changed your plugs? Sometimes some plugs (Bosch?) don't work well in our trucks.

 

When was the last time you cleaned your throttle body? Mine will idle rough when the TB is all sooted up.

 

Good luck.

[Steve Ks]

Recently my 1999 chevy z71 K1500 extended cab (70,000 mi) has been idling rough after it warms up.  The idle speed slows down to about 400 rpms and it acts like it wants to die.  It will catch itself and speed up but quickly slows back down to around 400 rpm and acts like it has a intermitent miss.  The only code I found on the OBD is 0300 ramdom misfire on multiple cylinders?  It runs fine at higher RPms and runs down the road just fine.  I have changed the air and fuel filter.

Any suggestions would be greatly appreciated.

 

<{POST_SNAPBACK}>

 

 

 

 

OK I changed my plugs and two on the passenger bank were pretty wet and black. I suspect that they were not firing properly. After the new plugs were installed it ran great for about 1 hour. Then the miss came back and the Service engine soon light came back on. Should I suspect a leaking fuel injector on these two cylinders? What else would cause these two cylinders to foul the plugs? I will pull the new plugs out tonight and see what they look like.

 

Any suggestions on how to test fuel injectors would be greatly appreciated.

Steve