That seems to be the way that Linus "walks". It's all stop (when I've made him stop) or full out until I make him stop again. After trying to get him to "Hold" unsuccessfully, I decided to take a page out of Linus' book. When he steps on his leash, he stops. He doesn't understand what's happened.
Sooooo, when he sped up, I slowed down and the leash tightened. He'd strain and I'd slow even more. Einstein loved this. He got to sniff & mosey & generally take his time. When Linus would stop pulling and slow down, I'd speed up a little and we'd all walk along. Until Linus would decide to speed up again. I didn't yell "hold" or "wait". I didn't jerk or tug on the leash. Linus looked back a couple of times but must have decided it wasn't me because he stopped looking. Which was the idea. I don't want to turn our walks into a bad thing in his mind. If his little puppy brain starts to associate straining on the leash (& gagging himself) with something he's doing and stops, then that's the whole idea.
The almost sea-sickness inducing lurching (fast, slow, fast, slow) reminded me of flying my R/C plane. I'm still getting the hang of it so sometimes I'll start porpoising. I'll start to dive a little, over correct & nose up too much, over correct & I'll dive a live. Get the idea?
Same thing with Linus. Surge up in speed, slow down in speed, surge up, surge down. Eventually he started to figure things out, get a little tired, and his speed leveled out some. We had a nice stroll after that. We heard some birds (Yes, I heard them. I need my full attention on Linus so the iPod stays at home.), they sniffed some bushes, everybody had a nice time.
No scary things happened until almost the end of the walk. We had a jogger on the other side of the road. A cat yowling. Each time he looked up, slowed down, and then went on.
Right now he's sacked out on the love seat resting up for bedtime. ;-)