98 mercury mystique- crank-no start issue.

[Majoroutlaw]

ok so we have a 98 mystique, 2.0l dohc. ive struggled with the vehicle for a week now to no avail. it cranks and is getting adequate fuel pressure (35lbs. i believe). when i started on the car the guy had it tore apart already. so i had to replace the starter. following that the crank sensor was broken, it got replaced. cam sensor also replaced. did a visual on the harness didnt see any problems, although i highly feel like theres a broken wire... somewhere. i replaced the pcm in the car because when i noid light it the injectors were not hitting rapidly, still the same result. im more familiar with gms but when i noid light it the injectors where not hitting but once every 2 secs or so. the ignition key was replaced by a locksmith because my friend lost his key. i have put new plugs in it. new coil, and new wires as well. good spark firing correctly good fuel pressure, but injectors not firing correctly. any ideas to help me out guys??? the car cranks and really struggle like it wants to start and sometimes itll chug start for a few secs and die again. ive tried starting fluid and carb cleaner just to see if i can get it running but it wont start even then. i do hear it back fire sometimes when it chug starts before it dies.
i took the valve cover off and timing cover off to check timing but the belt is good and tight no signs of wear, there are no timing marks on it but the cam slots line up how they should but the front cam vvt cam is off by 3-5 deg. i am told its allowed up to 15 deg. difference.
PLEASE HELP ME OUTTA THIS MERCURY MISTAKE... LOL