S.E.S Light Flashing?

alright, heres the problem. I have a 96 Blazer 4x4. I was passing a car yesterday, and the S.E.S light started flashing for about a minute, than came on constant. after work, i went and had the light read, and the guy told me it said Multi Cylinder Mis-Fire.

he insisted that i do a tune-up.
but i argued that i had just done a tune-up not even 5,000 miles ago, using all ac-delco products.

after getting the code read, i started the truck. and the light went out.

i tried to re-create the problem today, and it seems to be happening when the rpm's are up, and the truck shifts into overdrive? i could be wrong, but this is how it seems.

anyone on here have any clue what it could be? the truck doesnt seem to run weird at all when the light starts flashing.

i'd appreciate the help

Check with some of your local chain auto parts stores about a free scan then report the code number and we'll discuss it. There are a few things that cause a misfire, a code number will help pin it down.

. . . i had just done a tune-up not even 5,000 miles ago, using all ac-delco products. . . .
Did that include the spark plug wires? Cap - rotor?

it was new ac delco plug wires, and platinum plugs. and a new cap and rotor.

ill get the truck re-scanned tomorrow and see what code comes up.

the light just went back out, but ill see if anything comes up when they scan it again.

if the light was flashing than that means a multiple misfire. could be a multitude of things so when you get the truck scanned post the codes here.