How to replace cylider one fuel injector

You mean the rpms go to 2K? Have the codes checked again, write all codes down, so you don't forget. Some of the national brand autostores used to check some codes for free. The system might be in a fail-safe mode, as far as rpms?

With a miss-fire, I visually check for spark, Use a noid lite, check for injector pulse. Check compression.

To remove injector, make sure there is no fuel pressure on the system. Remove upper intake manifold. Remove intake supply manifold and injectors as an assembly. Remove injector in question.