GT-40 stalls when shifting into gear

[Kyfooter]

Issue 1). Engine starts and idles perfectly fine. No jumping around. However, when shifting into gear the RPMs drop 200-300 and it sometimes stalls out. Normal idle is around 700-800. Otherwise the boat runs really well. All spark plugs, wires, distributor cap and rotor were replaced.

Issue 2). Sometimes turning key will not even engage engine to start as if the throttle isn’t in neutral or the safety lanyard has a bad connection. Toggling the lanyard or shifting into gear then back to neutral does the trick. But how do I determine the culprit?

97 SN with GT-40 and 147 original hours.

[FMSKI]

Get a fuel pressure gauge and connect to see if pressure is to specification and is stable. I think it's about 40PSI.

[Kyfooter]

I have a gauge, but it's been many years since I used it. Care to refresh my memory on the steps and where to connect?

Also, what's the theory on checking fuel pressure? If it idles well, wouldn't it be getting sufficient fuel? Maybe my logic is off. I'll take all the suggestions you're willing to provide.

Thanks.