Spent A LOT (probably too much) of time instructing in the sim and aircraft in a previous life, here are some tips I learned over the years:
Know procedures cold. You don't do this stuff very often, so you don't have time to struggle with recalling what to do. But you know this already.
Now on to flying the sim. I'll elaborate on what chucky said above about setting pitch and power. We use to emphasize what we called "Control/performance" flying. (i.e. set the control instruments--ADI and thrust--and crosscheck the A/S, alt, VVI, ect.) My guess is that you slipped into Performance/performace flying and have picked up some bad habits like justt pulling the power back while starting down on glideslope and them modulating the throttles to maintain airspeed. (I've seen this happen to VERY senior experienced people, so it's not a "new guy" thing.) One can often do that in the jet because of the other seat of the pants cues (sound, feel, etc) that aren't present in the sim.
How to get better in the sim: Practice setting a specific power setting on final/cruise. Hook up the auto pilot for CRS/CS and manually set the power. Imagine you are giving directions to someone else whos flying (i.e "I see you're10 knots fast...set 52%") Do the same with pitch: "1/2 dot high...lower your pitch 1 degree," and course: "1/2 dot left, fly heading 127 to correct back to course."
Of course those were random numbers for example. But youget the idea.