CHEVROLET SUBURBAN ENGINE POOR MILEAGE

I Own A 1999 K2500 3/4 Ton Chevy Suburban With 156,300 Miles With A V8 7.4 Liter Vortec Engine It's Throttle Body Injection. For Some Reason...

Truck Runs Good, Idles A Little Rough. I Recently Changed The Spark Plugs And Cables Which Helped A Bit. Fuel Pump And Filter Changed A...

I Have A 94 Chevy Surburban On Which I Changed The Motor. It Sucks Gas And Backfires While Running. Is It A Computer Problem?

Ok My Question Is My Truck Seems To Be Losing Power And Has Really Bad Gas Milage. It Doesnt Buck Or Have A Hard Time Starting Nothing Like...