89 Evinrude 120 sputter and popping

Question
Ron, I recently bought a 22ft boat with a 120 V4 evinrude.  I called myself looking it over really good and the guy that owned it looked very trust worthy he had done a lot of good work to the boat.  He also told me that it ran out very well.  We cranked the motor before I purchased it.  Like so many others I didn't take it to the water for a couple of weeks.  Once in the water It fired right up and idled really smooth at 1100 rpms with no problem.  After letting it warm up for about 10 minutes while I was getting stuff out of the truck.  I started to leave the dock.  When I gave it throttle the engine started to hesitate and sputter at higher rpms.  You could tell that it wasn't putting out full power.  If I backed of the full to about 60% It seemed to smooth out but ran very slow and burned a lot of fuel.  About 8 gal in just over a mile of running.  I never got the boat to plane out and because of the consumption of fuel I had to have someone tow me in.  I looked at the carbs, they look new and checked the primer bulb and fuel hose, they are new.  I have very good spark from the plugs and from the coil.  It reminds me of a old truck I once had that jumped time but I don't know how to check the timing or if I am even looking in the right direction.  Thanks mike

Answer
Hi Mike...thanks for selecting the undersigned to respond to your question, but I'm not a mechanic.

The boat/mtr package was 17yrs old, and you claim the vendor "had done a lot of work to the boat", which should have raised a red flag to back away from making a purchase. Next time, engage the services of a qualified and reliable marine mechanic and get the engine properly checked out. In all likelihood, they'll save you a lot of money.

The fuel consumption indicates a serious problem, and I wouldn't anticipate an easy and cheap solution. If it becomes too costly, take your lumps, and get another mtr through a reputable source.

Safe Boating
Ron