BAD lean spot.... any suggestions??

If it will rev past the 1500RPM range, it's probably not the cat. When they plug, they will usually idle and operate at low RPM's (unless it's totally plugged) but not at higher RPM's. I would suspect the lean burn computer. Can you get it to hesitate and miss just revving it up in neutral? If so, put a timing light on it and see what the spark looks like when you get it to act up. If the advance jumps around or the spark disappears, it's probably the computer.