Maybe it is the ABS pump? That thing was noisy in my 4runner. Although, I have only heard the Taco make this sound on two cold start ups, and the 4runner would make the pump sound quite often. Cold and high elevation seemed to make 4runner sound louder and occur more often. My house is at 7,000 ft and I am pretty sure this made the pump work harder and more often.

Anyone hear nothing from thier 05/06 4.0 on super cold mornings at high elevation? That would suggest I have a problem.

2006 Tacoma Crew Cab 4x4 Auto TRD Off Road
2002 4runner SR5 4x4 79K miles (Sold)
1993 Pickup Ext. Cab 22RE 4x4 82K miles (Sold)
Park City, Utah