Hi I posted on here before and seem to have lost my original post, I really need some solid ideas as to what to have checked. I have a 2000 blazer with 260000k on it. I recently had new plugs wires cap and rotor put on along with some other work anyways 360.00 later this truck runs worse than before i did the tune up.
1. wont fire if the temps are cold even when plugged in

2. idles awesome but when on the highway it has a huge hesitation, so much that the tranny downshifts out of overdrive, this usually only happens when the weather warms up, runs OK kinda when the weather is cold

Any ideas of what to check would be greatly appreciated!! Take it back to a shop and it will cost another fortune!!!