I have a Simplicity ZT1500 with 25 hp ohv Briggs on it(44S9 77 0004 G1). Has been to the shop twice to no avail for a total of 35 days. They say they cant replicate the problem. Hour into mowing 2.5 acres it loses power and dies. STart it up and it dies. Done mowing. Nurse it back to the house...