I have a pair of 1977 Chrysler 360 inboards with electronic ignition. My one motor drops off RPM's at 2500 to about 1000 and jumps back up to 2500 until I slow her down. I can run for a while at 2300 RPM's with no issue. I have cleaned the Carburetor, replaced the coil, Ballast resistor and the Electronic Control unit. I have checked the secondary float when at the dock and the level seems to be good. The mechanical fuel pump is 2yrs old. I checked the weights in the distributor and they seem to move freely after I put some WD40 on them. Any advise is greatly appreciated.