Three basic approaches to this, each one gets more complex and costly.
1- Run a batch of Techron fuel treatment with a tank of gas. This should clean up most minor clogs
2- REmove the injectors and soak the tips in acetone for a few hours then blow them out with a 4-6 volt source and compressed air. (Major pain in the ASS!)
3- remove the injectors and take them to a shop that has an injector cleaning and testing machine. (In Phoenix there is a NAPA on University Dr. and McClintock) They will rebuild the injectors, new pindle caps, o-rings and wire baskets plus flow test before and after and also make sure the spray pattern is good and provide you with a printout of the results. Around $100 for 6 injectors. This is SO much worth the money! 20 year old injectors need to be cleaned. My engine runs so smooth it's like glass.
Steve is right on all accounts, but here is what I did. My '78 was running a little rough so I put sone fuel injector treatment in the tank. The car ran for one more day and stopped. I parked it and drove my other car for a while. 7 months later I went to work on it. The gas treatment had stirred up some crap in the tank and clogged the injectors. I flushed the tank and cleaned it real well. Then took out each injector and used about 20lb of compressed air and a 9v battery to open them up. She is running better than before and didn't cost me a thing.
Hope this helps you out.
JN Austin TX
BTW check your gas tank for rust, dirt, or corrosion because something had to cause your injectors to clog.