Johnson 150HP Non-VRO?

First I would like to say that I am aware that there are several things that could cause this but I have been down several of the roads already.

In 2012 I destroyed the lower unit on the 2nd Johnson 150 in the boats history on Amistad in Evans Creek. After extensive research not one could find a matching lower unit for the motor, so I purchased another used Johnson 150. Since then I have had the carbs rebuilt, replaced the spark plugs and all the fuel line and filters have been replaced with a new primer bulb. Then it was still running sluggish so I took it to Boerne Marine and they checked everything out, replaced the throttle cables and the magnets under the fly wheel. It ran great until a few months ago.

Here a few months ago it started a new issue and I am lost. When it is cold it has all the power it should, jumps right up on plane and will run 56-57 mph trimmed out. Then after the initial first run and it warms up it drags to get up on plane and when I get it there it will only run 48-49 mph. It feels to me like the timing is off or like it has lost the "power band".

Do any of you have any idea to what might be going on here?

Check your fuel supply hose from gas tank. Make sure it hasn't started deteriorating.

Thanks Tommy. I grew up in Rockwall and you have worked on this boat back when it had the original VRO GT 150 on it. The supply hose looks good and there wasn't even any trash in the pick up screen. I also checked the fuel pump screens and they were clean as well.

I had similar issue with this motor. Only mine was intermittent not just when warm. Mine haunted me for years. No one could fix. Then a very good boat mechanic that I know gave me a powerpack and said wire it up and go try it. Ran like a champ afterwards. I would warm it up in the yard with earmuff and then make sure you still have fire to every cylinder.

Power pack gets my vote

These Johnson and Evinrude motors always give me grief and I have found that if I will clean all grounds first I will eliminate 50% of the minor running problems. The other problem I have seen several times is the timing base sticking not allowing the timing to advance on throttle up.

Thanks for all the input, I have been thinking it might have something to do with the power packs and fortunately I kept the power packs off of the original 150. I will just have to dig through my storage.