On the end of the IP towards the firewall, there is the electronic idle control unit with a wire connector on top. Remove this electrical connector and see if that problem goes away to test the ELR. Some 602 engines also have a butterfly valve in the intake manifold on the passenger side - Not sure how this works but I've never heard of it going bad. My ELR does not function quite right but my IP doesn't do this. Its possible something in your pump is broken.

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Brian Toscano