Chevrolet Impala Engine Backfire

Just Had Oil And Filter Change, But When I Give Gas And Stay On Pedal Car Chugs Like It Is Almost Going To Backfire.

I Have A 2005 3.5l Out Of Saturn Relay I Bought Engine To Replace My Worn Out 3.4 In My 2000 Impala. I Changed The Plenum And Fuel Rail And...

Has A Hesitation When You Accelarate With A Backfire Sound

I Have A 1969 Chevy Impala That Is Sluggish To Go And When I Push The Gas Pedal Down All The Way The Engine Backfires. I Need To No What I...