2013 R Silverado S 1700 was running fine until I disconnected the battery to install battery tender pig tails. Now it lugs in all gears & max out at 65 mph in 5th gear. The air filter had condensation all in the housing. I cleaned the K&N filter, put new gas & some dry gas in it but not much difference. Does the ecm need to be reflashed after a battery removal? I checked the plugs & they have a good connection. It all started, as I said, when I disconnected both battery cables.