injector cleaning

I have an 86 park with 33k on it. Car sat for a couple of years. All ready had to change alot of parts on it. When car is in idle mode shacks alot. Even when driving at steedy speed car seems like it's missing. The last time I took it to the shop they told me to have them flushed. I don't think it's going to work. I have tried everything on the market. Do they do a power flush? I forgot I'm also not gettting any codes. Thanks for you help.