I know, sounds dumb. 1999 4.3 Vortec, 105K miles. My daughters carshe hasn't had it long, 1 oil change worth so I'm not familiar with the car. How much crap is on the passenger side that has to be removed before I can find the Valve cover?
She comes home late last night with horrible knock. The car ran great until she was about 300 feet from home. I'm hoping maybe a Rocker broke. It shudders on acceleration like we are a cylinder down. it is actually quiet until you give it a bit of gas. It was too late and the engine too hot and at that time of night I plain didn't care.
I heard these were strong engines, has anyone heard of Rockers breaking?

 

I had similar symptoms on a car I had years ago. Turned out to be a bad plug wire... It was arcing under engine load, fine at idle. Stuttered on acceleration.

Run the motor at night, and look under the hood. If it is a wire that's arcing, you'll see it...

 

That would explain the acceleration issue but there is a Knock. Did you have a Knock?

 

I did have a decently loud knock... Just try and take a look at it, doesn't cost anything, and you don't have to remove anything. If it isn't my next question would be does it do it when the engine is at operating temp only, or through all temp ranges?

 

Yeah it does it cold or at Temp.
Pulled the plugs on that side, They all looked nice and clean as they should , Gap was correct and they were all consistant with each other.

Took the passenger valve cover off...well almost, I couldn't get it past the harnesses that are wrapped all over that side of the engine. It was up high enough for me to discover that all the Rockers looked fine, damn it, That would have explained all the symptoms AND it would have been an easy fix. How does one take the Oil Fill Spout off the Valve cover? I thought it was a half twist but It didn't want to go and I didn't want to break it.

 

should be just a half twist.