Check your spark plug wires where they plug up to your optispark. Mine did the same after my rebuild and it ended up being the #8 cylinder was missing under loads because the wire was not pushed into the opti far enough. Good Luck.

 

Can you buy the OE coil ground wire anywhere?

 

I am having pretty much the same stumbling... I am pretty sure my fpr is leaking.. I can smell fuel in the vacumn line, my kirbin afpr came in today, I will put it on today and let you know if it helped with the stumbling...

 

thansk man

 

It sounds like you and I are having the same problems with our cars...

 

when i put the engine back in we didnt have the braided coil ground wire so i just used a simple black ground wire. the weird thing is the car ran great with the old LT1. then as soon as i put the engine back in it had a slight high rpm miss just at about 5500, and then it all the sudden went into this. so i am just seeing if maybe something went.

 

What gage is that "simple black ground wire"?

 

I believe its a 12.

 

took the fuel lines off today to take the manifold off and not a drop of fuel came out,,, I am really leaning toward a FPR now. can that cause the stumble?

 

Yes if the diaphram broke inside it, its just dumping fuel into the engine.

 

Damn I was looking for this post... hey sean1997ws6 ,update I put the new afpr on their still having the stumbling issue... just to let you know. I am getting dynotuned on the 1st. hopefully that will clear it up.. anyway when you pull off the vacumn line off the afpr can you smell fuel? I put on my new one and I can still smell it, I am thinking from running really rich at idle, come on new tune...

 

my stumble happens off the line or when cruisin if the rpms drop between 1-2 rpms then i get a bad stumble also and it backfires pass 2k though....., and its all good weirdest thing oh yea and the car is fine at idle

 

Too small. The grounds return all the ungrounded power loads to the chassis. Look at the width and thickness of the ground straps.... way more conductor area than a 12-gage wire.

 

is there anyplace i can get an original wire?

 

problem fixed.. turned out to be the coil ground wire broke down. put a new one on and shes back.