My answer to the original question would be that it can't hurt, but the problem you are experiencing could simply be diagnosed to such a problem by watching fuel pressure during the event.
As to the mess from the other tank, it must of been a diesel. KE cars really don't take well to contamination. On many models we will pull the tank sensor and look in the tank with a light.
BTW, if you find it rusting, get a new tank.
Bosch Master, ASE Master, L1
33 years MB technician