Hi all. I'm a new owner of a 2001 Blazer. The PO said he thought it needed a tune up, but I'm not so sure. Here's the problem, yesterday I had less than half a tank of gas, it ran alright missing at times. But I filled up with gas, then it ran rough as can be, quitting 5 or 6 times. I don't know if a tune up would cause the symptons or not. When running 55-60 mph I'm right at 15-1600 RPM, but watching the tach, the RPMs jump up and down a couple hundred RPMs. Thanks for any help/advice given.

 

And fuel mileage is terrible, 143 miles and it took 14 gallons to fill up. Good thing my gas is paid for at work.