Despite the fact that you just got it back,
this sounds like a hung valve, 1-bad wire, or a simple case of timing.

When post-shop performance = worse than when you first brought it in, something needs to be done.

Ask them to throw it on the diagnostic computer,
and have them take a look .... it'll be worth the few extra $$$ for you to do if they charge you.

On most cars it means you need to put air in one or more of you tires. You may want to try reading your car manual, it has all kind of information in it.

Pull the cylinder 3 spark plug and smell it. If it smells like gasoline, then there is a spark problem (bad wire, or coil, or plug). If it doesn't smell like gas, then verify spark, if spark is good, then swap injector 3 with injector 4, and see if the problem moves to cylinder 4, if it does, replace the injector.