have a blinker problem with my 1999 ford explorer?

If, when operating the turn signals, the clicking noise inside the vehicle speeds up, the sound is there for a purpose. It's to notify the operator a light is burnt out. NOw, if the problem in intermetent, meaning it clicks fast at times and normal at others, there is a good chance you have crud or corrison built up inside the socket holding the light preventing proper contact.

Come to think of it, I've had a couple of broken wires and/or connectors at the back of the multi-function switch that caused this kind of symptom. If all else fails, pull the steering column cover and wiggle the connector at the back of the T/S switch while watching its operation.