95' winstar 3.8l obd-II code p0305 misfire on #5 detected

my brother bought this because "it looks good and the motor just needs rebuilt". now i warned him thats its a computer controlled car, but what do i know. well he rebuilt the motor. of course he had to go out and by the cam position sensor alignment tool. there's 20 bucks he'll never see again. but he gets it all back together and it fires up. just runs real rough. he then went out and bought a code scanner which gave him a p0174 adaptive system fuel to lean on bank 2. so he got some used injectors from a junkyard and now it have him the same codes for too lean on bank 1 and 2. i did some research and found some sites recommending to replace the fuel filter. he did and the codes p0171 and p0174 went away and where replaced by a p0305 misfire on #5. now we can pull the plug wire off on #5 or #6 and the engine runs about the same as it does hooked up. a studder can be see with the timing light hooked up. too me it looks as if the ignition module is shit. but since its controlled by the computer could it be something else is bad? at this point he doesnt want to spent anymore money since the scanner he bought give you a pretty readout but still doesnt tell what everything it shows you means. the code scanner does list items like fuel trim and its saying its like 0 for a like 1st one and a few others.
anything else we should check that might be another hidden code?

Sounds like your coil pack is gone. I believe #5 and #6 share a coil

we tried that still the same thing

The coils are shared 1/5, 2/6, 3/4
Check the plug wires at the ignitionc coil pack--

right side back to front is 1 2 3
left side back to front is 5 6 4

There may be a label on the block showing the pattern.