Might try myself?
 

Saw this over on Boss 302 forum, price not bad. Performance Chip Tuning Racing ECU Car Chips Power Super Flash Do know from several past cars these can make a night and day difference. Not anything radical, A spring cleaning thing:)

Auto manufacturers tune there cars for middle of the road, every scenario imaginable that may be encountered, much can be unleashed. Would like to see our LaCrosse get a bit better mileage, not 1/4 milking (lmao that came up instead of mile-ing) car at all.