American Pacesetter, Newport Beach, reported a drop of 37% in net income for the third quarter, to $580,000 from $918,000 a year earlier. Revenues rose 18%, to $27.9 million from $23.7 million. The company reported net income of $1.69 million for the first nine months of the year, contrasted with net income of $1.7 million for the same period in 1986. Revenues grew to $72.6 million, a 17% jump from the $62 million posted last year. American Pacesetter consists of two primary operating divisions: Pacesetter Homes Inc. and San Clemente Savings and Loan, which operates five branches in Orange County.