Unfortunately, backfiring in the intake usually indicates timing issues. It does verify spark though.

You might try smacking the base module around a bit. Another way of getting timing issues is to have intermittant timing or intermittant ignition in general. The base module is like a OVP in your car and powers the ME module.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician