I had a very bad hot restart problem. It was so bad it cranked slowly as if the battery was weak...The problem eventually turned out to be bad primary injectors.
David, that really seems unlikely that the fuel injectors going bad could cause the starter to not have enough power to turn the engine over with authority.
If you look at Section ML sheet 4, you can see that the starter motor is directly connected to the battery positive terminal through an unfused connection to a big relay with large gauge wires.
All 10 of the fuel injectors and the primary fuel pump go through a 25amp fuse, section ML sheet 5.
25amps is chump change compared to what a starter pulls. Most small batteries can do 800 cranking amps.
I don't doubt that fuel injectors go bad and need replacing, but I really doubt that bad injectors could cause the starter motor issues you saw unless the cylinders were being filled with so much gasoline that the starter couldn't turn the motor because of the increased compression. But I am sure you would have seen some other explosive symptoms if that was the case, and the car wouldn't run at all, not just be hard to start.
I am thinking by doing the work that including removing the plenium, you must have somehow improved the connection to the starter or the ground wires since the starter is accessed through the plenium too. So you would have fixed 2 problems instead of 1.