Loss of power on 351W

[BeagleRock]

I finally got to do a real road/highway test yesterday, in town she runs great. So I decided to take her out on the turnpike, floored it from a complete stop and was going good until about 2 seconds into 3rd gear and it was like the fuel was cut off, let up and went on as expected except the cruise control couldn't seem to hold a set speed. It Rev up and down up and down. Tranny is a C6. Any suggestions welcome!  
 Thanks Randy
Timing is at 8* although it does have a cheapo HEI dizzy. Seems like a fuel problem though, I'll check tomorrow with a cold engine to see if choke is not properly set.

[Gary Lewis]

Could still be ignition, but fuel seems more likely.  However, I've forgotten what all you've done, and as this is a new thread I can't tell.

But the choke staying on, or partially on, might do it.  And a failing ignition would do it.

[BeagleRock]

Right Gary, could be either, but I'm leaning towards the carb because when I got her home I floored it in the driveway and the first time there was a big hesitation. The second time no problem!  I wished you lived in Wagoner or somewhere a little closer and I'd drive her to you. Anyway I just woke up and think I'll wait until tomorrow to see if there's anything obvious.
 Thanks Gary TTYL