It sounds like you have air in the lines, the seals at the IP outlets are probably the source of the air, there are O rings that can be changed and a minor overhaul of the Ip is probably in order. Is it also leaking oil at the end nearest the firewall?
Whats the history on that engine BTW? Original #14 head? Run it down to San Mateo, I know a place there that will put it right if you don't want to mess with it yourself.
Be aware that a member of the Shopforum here was experiencing a rather large amount of fuel leaking from the IP, and his engine (OM603 in an SDL) suddenly caught fire recently, the entire car was lost as a result before he had time to have the seals replaced.

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