I bet there is a vacuum leak somewhere in the yellow line that goes to your front axle, at higher engine speeds there is less vacuum and it could cause your free wheeling clutch to 'flutter' on the highway.

angelo: I am not so sure it would be your ecu. if you can find the wire that is going to your front axle, try unplugging it and see if the blinking changes. if not, then try grounding the wire that goes up into the truck, see if that changes the blinking.

scottie

97 Montero SR w/Mitsu Adj Shocks & Rear Diff Lock ARB Front Diff Lock 4.9 Ring/Pinion 3.15 transfer box 43:1 crawl ratio 2" suspen lift 2" body lift 2" Gas Tank Lift 35x12.5 MTRs 15x10 Wheels Rock Sliderz ARB front bumper w/12k winch Custom rear bumper