Doesn't look like it to me. I learned the vernacular on this site after joining. Lots of learned folks that had careers in exciting aspects of boating and shared their expertise. A few of them left.....Faztbullet for one. On the performance of a bow lifting prop, I learned that first hand. I experienced it before I knew what I was experiencing.....the Ranger and riding on a pad back in 1989 when it was equipped with a Quicksilver/Mercury Laser SS prop (the first edition, not to be confused with the Laser II).
The prop shop is the right answer. Ensure that whatever you test is ported, like your Tempest, as you are used to that and like the hole shot. The black things in your prop holes are plugs that come in various sizes and the size determines the amount of spin up you get in the hole. Too large and your rpms run up too high and you take forever to get out. Too little and your high pitched prop is a dog in the hole. You apparently are running the right size as you are happy with yours and your test prop(s) should be ported. The Laser II may be a good place to start if they are still available. I am not familiar with any current props other than the Ballistics I ran for the last 10 years which had all the goodies but porting and I ported mine just to have something to do one day, but really didn't need it as the boat in my picture is alum with the right hull and hole shot was a no brainer .
Looking at a '94 Mariner sales brochure in the 135 to 200 hp sized engines, they advertise power movement of the engine: -4 to +20 is the range of the power trim and that is measured with the engine vertical but does not specify the tilt angle of the transom bracket for the measurement. From +20 to +75 degrees it is tilt only.
Also in that sales brochure I noticed Laser II Props in several of their pictures so that tells me that they were as hot as their predecessor and Merc/Mariner is not ashamed to flaunt them. They are SS, ported, cupped, and high rake....all the goodies. Quicksilver Mirage is posted in that catalog too but I don't see any ports and you have already proven to yourself that your replacement needs to be ported. I'd start with the Laser II from your prop shop in addition to what they may recommend. ensure that your take your pictures of your setup with you and your numbers......on your numbers, one thing that I didn't see.....how did you measure your mph? Meter or GPS? If meter, that could be a source of disinformation which could drop your slip number if in the right direction, but will have nothing to do with your being able to trim up till you blow out.
When you get to the top of the trim piston, the tilt mechanism takes over and can continue to lift the engine but only if it has more power than is applied to the lower unit via the prop turning. If the prop is turning too fast.....slightly above idle rpms, it causes too much pressure on the piston (like in a trim situation) and the tilt pressure relief kicks in and bleeds the pressure back to the upper end of the trim position....+20 degrees from vertical plus some transom angle.
As mentioned herein buy Mr. bgagnon, your trim may be bleeding down due to faulty system pressure. One way to find out is to drive your engine up to about 20 degrees above vertical and let it sit for a week. If it's still there or reasonably close, I'd forget the trim malfunction idea.
I disagree with Ski Dad on his suggestions and I have talked through my differences in my replies supplying reasoning for my opinions.
