Go get a compression test done... honestly it sounds like you may have some bigger issues going on with that engine.
If the compression test comes back poorly, you might want to opt for a leak down test as well so that you can determine exactly what the problem is.
Purple Cleaner will dislodge a lot of the carbon and "gunk" build-up which can in-fact clog injectors up even more.
You might actually need to take the injectors out and have them sonic cleaned by a professional service.
^ That is a reputable service they will even flow test them for you and give you a report.
Best practice is to label them in separate ziplock bags with which cylinder number they came from so that you can put them back in the same place.
Hope that helps, let us know what you find out.