Mine were stuck pretty good when I swapped them a few weeks back.
Before I removed them, I shop vac'd as much loose dirt from around the injectors as I could, then I soaked the area around them down with carb cleaner and cleaned it all up nice and shiney.
The open end wrench trick works, I would also suggest to just be sure to wrap the hard wrench surfaces with a layer of duct tape, and/or stick a shop rag or something soft between the wrench and intake as you pry about or you might do a little damage to the intake.
If you're removing the rail with the injectors still in it as recommended, getting them out of the rail is fun too. Just pin it down to a bench with one hand, grab hold of the injector with ther other ,ad start wiggling, twisting and yanking until it comes out. They will come out.
Once I had the injectors out, I soaked some q-tips with carb cleaner and then carefully cleaned out the injector openings in the intake and fuel rail until all the gack was gone.
Lubed up the new rings on the new injectors with a thin layer of vaseline and slid the injectors home in the rail, then put the assembly back on the intake...popped right in.
If you disconnected the TV cable from the throttle body like I did in order to have more room to get the rail out and in, be sure you readjust it properly before you go out driving around or you may hurt your transmission...
Tim