my 99 trans am is pulling a P0300 (multiple missfire) i have Ngk Tr55's with MSD wires. the code is on then goes away. back and forth. ive changed the spark plugs around, changed the wires around, and the spark plugs are normal. nothing out of the ordinary. i need to fix this before i put my cam in.

 

http://www.gearchatter.com/viewtopic8880.php

Here you go. Seems you have the same problem I do. Mine does not have the ses light on. Cost...
$57 chevrolet dealer
$34 Oreilly

I had to use an oscilloscope of my sensor to find out what was going on.

 

what oscilliscope did u use.. cuz u cant hook an osicilliscope corretly.. u have to use a scanner.. do u go to uti in tx???

 

My older brother is a mechanic, and his shop has a Genisys scanner/computer. That thing is pretty cool. We logged on the sensor on the osciiliscope and went back and took a look at it. Found out the signal was not a constant signal, it would do like one ong signal then a few short signals and do them randomaly.

 

so it was ur ckp sensor?? if it was that why wouldnt u have a check engine light??

 

I have read that some people get the light and some don't. The only coe that was even stored was an 02 sensor Bank 1 code about it not switching fast enough from lean to rich.
I am changing it out next week, due to no funds this week.