PROBLEM SOLVED! All Ilfochromes came out very clean, no more yellow, green or brown staining on back of prints. Per information from the Ilford forum I changed two things:
1) Changed from using distilled water on all chemistries and rinses to a normal hardness (bottled drinking water) to mix all chemistries and for the rinses. This is probably what did it.
2) Used only ONE rinse after the developer step and for the exact volume and time (30 seconds) . ( I previously used a larger volume on 1st rinse than the normal chemistry volumes. But apparently on this 1st rinse step, it's important not to over-rinse time or volume wise)
I just wanted to post this info in case others come across the same back-of-print staining problem with Ilfochromes I had previously encountered.
PS: I also used contrast reduction making for the first time, and see a 100% improvement in the quality of the Ilfochromes.