Help with code p0430

I have a 99 Suburban 1500, 5.7 with 113,000 miles. I had the intake gasket replaced about a year ago. The vehicle then started misfiring when pulling a trailer. I started getting a p0430 code and had a friend with a scanner read it and he said the misfire history is Cyl. 1-0, 2-298, 3-11, 4-1193, 5-341, 6-0, 7-197, 8-0. he reset the computer and I got a p0307 code for misfire on cyl #7. I had the wires and plugs replaced when the gasket was done. I replaced the fuel filter about a year ago. When I drove it last it misfired when it was cold. I drove about 15 miles turned it off then when I drove it again a few minutes later it ran fine and the check engine light p0307 went away. My friend said he believes the CAT is okay due to the readings on the 02 sensores. Any help is appreciated.

Miss fire or miss or running rich is the main cause of code 430.
Work on that miss.
Drive it a little and recheck miss fire history.
Are you using good AC delco plugs.
Is the fuel pressure up to par running on the road?
Good Ac Delco air and fuel filters?

I had new plugs put in about a year ago and the mechanic used Auto Lite plugs. Air Filter is a Fram. I will have to get fuel pressure checked I do not have that tool. Do you think the p0307 which is #7 cyl or the other cylinder misses is the reason for the p0430 code. Could the distribitor and rotor be the cause of this? Again thnx for the feedback. This all seems to have started after I had the intake gasket replaced

Miss fire or rich running is a leading cause off cat code.

The dist Camshaft off set on dist rotor pointing can also cause missfire,

Pitch the auto light iplugs in trash can and get the right AC delco plugs in it.
And go from there.

So, Off topic, Sorry, ACDelco plugs are strongly recommended?
What about for say, the Bosch Plats or something?

So, Off topic, Sorry, ACDelco plugs are strongly recommended?
What about for say, the Bosch Plats or something?

Do a search (web and this forum) and you will see that they have caused many issues in GM engines. Best bet is AC Delco plugs.

//2000CAYukon

agree with Yukon and MT on this 100%. on my old 79 beater pickup i had, i ran champion plugs, and were great. on my 98 s-10, i run nothing but AC plugs. anything newer now days you need to run what came in it. motorcrap for ford, bosch or whatever came with it for dodge, and AC Delco for GM.