I have a 1995 Chevy Silverado, 350, 2 wheel drive. I have been letting my dad borrow the truck for about three weeks and the check engine light has been coming on and off infrequently for the last six months. We took it to a mechanic, but the light was not on, we had a few sensors replaced and went on our way. Everything has been running fine. I then got it back from him yesterday and the light was back on, it had not been on for about a week or so. Then when I was driving it, it started shifting hard. Meaning it would rev-up a little higher then normal and then give that jolt into second gear. It did it a little less from second to third, but none-the-less still jolted the car a little. Is there anything I can do besides change the transmission fluid to alleviate this problem? What other suggestions do you have before this problem gets worse? Have you ever heard about a "check engine " light coming on for a day or so and then going off for a week and then coming back on again? It's like a kid going to the doctor, anytime I have a chance to take it into the shop to find out why the light is on, it goes off again, and the truck has been running great up until yesterday. Just looking for some suggestions on the light and some help on my transmission. Thanks!

Furthermore, I just talked to a friend who had heard of a process of tightening the bands on your transmission. Especially in my circumstance where the transmissions jolt is mostly from 1st to 2nd and then exponentially BETTER from there up... Just let me know. Thanks.