Help! My A60's Engine Won't Rev Past 3k RPM

My '95 Toyota Corolla A60 has been experiencing a strange issue lately. The engine refuses to rev past 3k RPM under normal driving conditions, despite having a full tune and upgraded camshaft. It's not sluggish or hesitant, just won't go beyond the 3000 mark. Anybody else experience this problem or have any ideas on how to fix it?