2004 X-Type 2.5l won,t start after replacing battery?

[21sprint]

It has been to a dealer in St. Louis and they said $1800 to even try. These folks thought I might be able to help or sell it for them. The engine back fires sort of like out of time but only has about 75,000 miles on it. Plugs are fuel fouled so I replaced all 6 of them. While I had plenum off I checked injectors for pulsating and they was. Car had 41 lbs of pressure on the electronic pressure regulator and plugs are firing. When I just hit key fast it sounds like it might take off, but if I hold it down and crank it back fires through plenum.