I just bought me a (New to Me) 2004 Hustler Super Z 60" mower w/a kohler 28hp EFI engine. This was a trade-in with 1100+ hours on it. I had the chance to really run it hard the other day. 3 different times the motor seemed to loose RPMs(like it was starving for fuel or the governer was not working right) No missing out or rough runing it just slowed down(rpms) Each time, when i let up on the directional levers, it recovered. & no it wasn't in very thick grass a couple of times. I continued to mow for a # of hours without a problem. Since this is a EFI engine, i thought it could be in the control module but no flashing light to indicate any DTC codes. Any ideas? I went & invested a fortune in a new filter(40bux) & have mowed in simular conditions & it did'nt do it again. Could that had been the problem?? Also WHY is that filter so damned expensive??? Is it lined with gold or does it have precious metals inside it??? 40 bux for a little steel can seems HIGH since a fuel filter for my duramax is less than that!!