I have a 94Z and have about 800 miles on a new 385. When just cruising spark advance will fluctuate and go up to as high as 47* and at idle might be 30* all the while the knock count is steadily increasing to as much as 56000 on the last drive I took. I had noticed it was a little sluggish off the line in normal driving and occasionally had a slight miss at low rpm. The motor is quiet with no internal noise, no header leaks etc. Could this be an Opti problem, Bad gas ? I'm not seeing any codes or ses light. Any help would be appreciated.

 

Those numbers don't sound too unreasonable.
Is the knock count increasing steadily, or just when you hit bumps.
Any actual knock retard?

If I had to guess it might just be false knock coming from something, maybe some bad gas, but probably just a tad bit too much timing in the program.

 

Dan K, The knock count is increasing steadily and I am getting some knock retard 3-5* . The motor is 9.5 CR so I'm not too concerned about detonation but am wondering what changed because it wasn't doing ths for the first 700 miles or so. Do you think it could be vacuum? My gauge hasn't changed so unless it is a minor leak I'm not seeing any change.

 

Update- Found a vacuum line unplugged at the back of manifold. I think thats probably it. Thanks for the help