I have a 99 silverado with 63,000 miles on it. I have a k&n cold air intake and for about the past few months my truck will be "groggy" like it doesnt want to go when it first starts running. I can have it floored and be turning 3000-4000 RPM and going 40 mph. Then all of a sudden it will take off like it should when it's floored. Also sometimes when I back up it will sometimes die. It just seems like at low RPM i have no power. My 2 ideas are mass airflow sensor and maybe new plugs & wires. But their is no check engine light or anything coming on. I have changed fuel filter and tried putting in sea foam along with lucas oil injector cleaner numerous times with no results. Any suggestions or thoughts I would really appreciate. Thanks guys!