I have a 1984 Merc 90hp 2 stroke outboard. Took it to shop said it had a coil out and bad ignition switchbox. Should work fine now. Sounds fine but still hard to start in the water and has no power. when cold max rpms are 3000 and when it warms up it went up to 4000 and thats under a load. Took it back to shop he checked the timing, compression check, electrical, ended up replacing spark plugs and kitted the fuel pump. Still no power and hard to start in the water. Well 800$ later boat still running like crap. Any suggestions? and what should that motor tach out at?