Won't run and is blowing back through tbi

Won't run and is blowing back through tbi Died on me while pulling my 5th wheel. Acted like a timing issue. Double checked my timing and discovered a fair amount of corrosion in the distributor. Replaced the distributor and plugs. Pulled the tan with black striped wiring to set ecm in bypass mode and manually set timing to 4 btdc. Still not trying to fire up. I have awesome fuel pressure and spark but not running. Please help!