[rwest]

I can’t give you a definite answer, but can give a few thoughts. Around town, you are stopping and going, on the freeway, once you get to steady speed, you keep it there.

So, is there something that is causing a bunch of fuel to “dump” into the system when first applying the pedal? Maybe a distributor issue not properly advancing or retarding until it spins up fast enough?

Good luck, it will be interesting to see what the cause is.