Johnson 175 RPM -

[doitureselfer]

I have a 1988 175hp Johnson with VRO...... unit runs fine most of the time but maybe once a day it will while running at say 4000 RPM drop off to 1000 RPM without warning and run @ 1000 very smooth for varying lengths of time... throttle still wot and then take off back to 4000 rpm. Darn near threw me out more than once. Compression is 115 psi across all 6.....??????

[boats.net]

Need to have the ignition tested to see if losing fire at time it looses rpm's.