I have a 2003 Chevy S-10 (4WD ZR2 suspension extended cab) that is having some hesitations while on the freeway. It always occurs as I get on the freeway and then stops as I get about 5 miles on the freeway. The hesitations are slight and doesn't seem to be affecting speed and I notice the tachometer jump up about 200 rpm when it occurs. It will happen numerous times as I drive.

The transmission drives fine with no slipping or hard shifts, the truck drives fine without any issues on the main highways around 45 mph. If I had to trigger a speed range when the problems occur I would say between 50-65 mph.

It's hard to figure out where to start looking for this issue since it only occurs when getting on the freeway and there is no dashboard lights popping on. Truck has 148,000 on it. Anyone have any ideas?

 

I have a 97 express 2500 van with the 5.7. I experienced something like what you describe, my van would occasionally hesitate at freeway speeds, but it did not go away with time. It turned out that my distributor was one tooth off. A friend of mine is a very good Chevy mechanic and it took him a couple days to figure it out. Initially he thought it was something in the transmission. Now it's smooth and gets a wee bit better mileage. Hope this helps, good luck!