Ok, I'm really, really, really lost here. I put in a points distributor from MOP for a short while until my HEI arrived. When I took the Jeep out it started and ran well. I took it out on the hiway. When I did it started sputtering, and bucking and lost power until I slowed down and turned off the road. I figured it was just because I didn't have the vacuum advance hooked up. So last week I put in the new HEI. It did the same thing. So I bought an adjustable vacuum advance unit. I followed the instructions with it and in Rich Mott's article. In gears 1 and 2 I could run it up to 4k with no problems. Put in 3rd gear and it chokes, sputters, coughs, doesn't backfire though. It runs great at 45 mph, less than 2500 RPM, in 3rd. Faster than that it bucks. I plugged the vacuum advance thinking that was it. Still does it. Yesterday it did it in 2cnd gear at higher RPM until I backed my timing from 10* advanced to 5* advanced. I thought based on that it was related to the timing. I've advanced and retarded it. Disconnected the vacuum advance etc. to no avail. Like I said, in 1st and 2nd it will run all the way to 4,000 RPM, but soon as I put it in 3rd to try to keep the speed above 50 mph that I was going in 2nd and it just falls flat on its face until I slow down to 45 mph or so. I'm stumped. Any ideas?