Like the title say after i changed the spark plug and wires in my 08 i drove it and at idle if it sits long enough it will start pulsing every few seconds. The truck shakes a little and the RPMs drop a bit then go back to normal. I used Ac delco iridium spark plugs, with MSD 8.5mm wires for a 99-07 truck. Could the wires be the problem although i wouldn't think it would be? I know all spark plugs were locked down just right. What do yall think could be up? Is the computer learning the new thicker wires? Idk but in advance thanks!

 

i had a bunch of problems with MSD wires.. i got the cheapest ones the parts house had and no more problems..

i even got MSD to replace 4 of them and still no worky..
put your stock ones back on and see what happens.

 

I think anything from msd is junk. I make my own wires.

 

Did you use diaelectric grease?
That's an insulator not a good conductor

 

Yeah I think I may send these back! No I didn't use the grease. Probay go back to go old ac Delco

 

8.5mm msd wire worked great on my truck. you need to make sure they are 100% on the plug end.. they can be a little tricky

i would put the stock ones back on. if the problem still persist you may have cracked a plug..

 

Crack the porclein on a plug?

 

Shi i run TR-55 (5.3) an TR-6 (6.2) bosch wires. Cheap plug and wire change with no issues

 

Trucks getting the 4.56s installed right is so ill do investagation when it get back.

 

Ive had 3 sets of MSDs and never had a problem. If I had to guess, you may have cracked a plug.