Had a new throttle cable put in, ever since then car wont slow down. on 2007 Chevrolet Avalanche

Idles normally. When I let off the gas it doesn't really slow down takes 8-10 seconds to drop 5 mph.....

Asked by for the 2007 Chevrolet Avalanche
Many times when you do anything with the throttle or throttle body, you have to have the system reprogrammed. Dealerships or shops with the proper computer are the only ones that can do this and cost is $120 and up.
Thanks! I'll take it back to the place that installed it.