1982 Johnson 70hp not reaching max rpms or power

[CornCob]

Hi everyone long time lurker on the forum for info and learning new things but I’m finally at the point where I have an issue I can’t seem to figure out a problem and I need help. I recently bought a 1985 Cobia 156 with a 1982 Johnson 70hp outboard from from my uncle that had been sitting for 10-15 years. I replaced the fuel tank, fuel lines, fuel pump, fuel filter, spark plugs, wires, coil packs, water pump, battery cables, rebuilt the carbs, and cleaned multiple connections on the motor. But for some reason it lacks power and cannot max out rpms. It was running great before it was parked in the garage but on perfect conditions I can’t get over 28 mph and 4200 rpms. Even in neutral on muffs it won’t go higher than 4500 rpms. I’m pulling my hair out trying to find this ghost any suggestions or ideas would help at this point. Thank you for your help.

 

[flyingscott]

What is your compression ? Does.spark jump a 7 /16" gap?