If you want to see what one blocked injector does, pull out one of the plug leads, and do a mag check. When the cylinder whose plug you pulled has the other plug not firing as well, the engine shakes like hell. You can't miss it, especially at 2000rpm.
Perhaps partially blocked is a better description.
Very recently an aircraft I fly had a problem that was diagnosed as a blocked injector. It manifested itself as a consistantly higher EGT on one cylinder and a higher CHT at high power settings on the same cylinder. The engine other wise ran smoothly and there were no other symptoms. In fact without the engine managing parameters the problem would not have been noticed. Certainly there was no shaking at any power setting.
On the other hand when I had a split diaphragm the symptoms were very much more as you describe albiet the engine ran rough as opposed to shaking itself to bits.
Finally on the occasion there were two dead (or perhaps badly contaminated) plugs in the same cylinder even at low power settings the engine was very rough with no EGT and CGT readings on the cylinder in question.
Two different engines and three different occasions (one six cyliner and one four) and I guess in a four cylinder engine the symptoms are going to manifest themselves in a more pronounced way.