With the engine running, the injectors are fully 'on' almost all the time. Shutdown is only during some decel conditions, and with the engine off. So, leaky injectors are not going to cause your problem. Leaky injector seals will cause a lean-run condition.
Interested in what you find with the fuel distributor. Good luck!
'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7