2002 GMC Yukon XL 1500 - Misfire

[francis x talamante]

we have a 02 gmc yukon xl k 1500 with misfire problems, the coils for 3,7,5,6 and 1cylinders hav been replaced before with the vehicle coming back with the same problems.the oxygen sensors hav also been replaced along with plugs and wires,both knock sensors,with harness. the vehicle has 107526.3 actual miles, the wires hav been checked from the coils to the computer with a dvom and all checked out good.misfire keeps coming back on number 1 need help ,suggestions ,tips please by the way codes p0300 and p0301 are present

[steven kiser]

if youre not pulling codes i'de throw a reburn at it.

[Stewart Levy]

Do you have the capasity to run a bleed down test on the fuel injectiors? what dose the plug look like thats missing

[francis x talamante]

yes i did a injecter bleed down ,all checked above specs and plug is new and not fouling out .the misfire seems 2 happen more when i accelerate and decelerate. the check engine light comes on then goes off when the vehicle sits at idle.

[Stewart Levy]

Hate to say this you might have a bad valve spring Iv'e had a bunch on this engine And the 6.0

[steven kiser]

since the conception of the pcm in gm's there is always the possibility of a bad pcm. i could fill the waiting room with pcm's that have caused intermitant skips. i'de check the harness and if it's ok seriously consider the pcm. bad grounds can an will cause this issue as well.

[ricmorin]

Just had one similar. Had a plugged cat.