19974 cyl running problems

[powdergiraffe]

I've been having problems with this 97 4cyl. It runs great around town with no signs of any problems. But if you drive on the highway for any extended amount of time over say a half hour or an hour it will randomly sputter and die. Usually when you push the clutch in to stop or shift. I finally got frustrated and took it into the shop and they drove it around and couldn't get it to do it or course. Its a great little truck but I'm afraid to drive any distance in it right now. It was having this problem last year when my girlfriend was driving it on an extended roadtrip. She took it in and they replaced the distributor. It seemed to fix it for a couple days and then it came back. Where should I start? Not really sure.