1998 Chevy S-10 Pickup, 2WD Problems

[tremethick]

Hi just bought the truck in the title a few weeks ago. It has run great and I have 1 year warrentee on the engine and drive train. It is only a 4 banger.
I have two questions:
1. The Service Engine Soon light has come on. The owner's manual says I should tighten the gas cap. I did, it did not work. Then it says I may have purchased inferior gas. I just filled up when I got the light. So, do I just run this tank dry and fill up with premium or is this a problem I should have a mechanic look at?

2. This is an automatic, wife wanted an auto, in D it seems like the tranny is very sluggish to get going. I have to drop into 2 to get a good hardy jump on traffic and 3 just to get the thing moving a little. If I play with the gas in D and hit it, let go a bit, then hit it again, I can get some pick up but it seems sluggish. Is this normal for this vehicle or should I have it looked at?

Thanks for any solutions.