I have an '88 Formula SR1-311 with 454 Magnums and Bravos. The port shifter has been acting a little odd, nine time out of ten it's fine, but every once in a while when I shift into forward it doesn't quite engage fully.

It's in gear, but the shifter doesn't go all the way forward and lock into position. Sound familiar to anyone? I'm hoping it's just an ajustment

Check the cable too make sure it is not stretched and out of adjustment. Does not happen to often but is an easy check.

Sounds like freyed/binding cable.

Pull the drive off and look at the cable, if it looks good pull the back cap off and make sure the allen head bolts in the shift rod/fork/linkage are in tight..

Hope this helps.
D*ck

Check it out and if cable get fixed right away. Had friend that had same problem & one time he hammered the throttles thinking both drives were in gear. Turns out 1 was out of gear for a few seconds until the rpm of the motor got to around 5000. Good part is it only bent the prop shaft when it went into gear.

Remove the shift cable to drive at the motor plate and shift drive by hand then check your cable alignment on the plate, this will tell you which cable is out of adjustment or whether there may be clutch issues.

Also try shifting the drive into forward while turned hard to port then to stb, this will show where the cable may be binding.