help 89 240sx sr20 wont start but cranks.

[andres_240sx]

just bought a 240sx with sr20det for cheap because it was blowing ECU's. fixed that problem, everything was spliced into,(HORRIBLE WIRING) it had remote start, alarm. it was a mess.
anyways got it running but was breaking up. it had 3 holes in the cold side intercooler pipe. 'replaced that'. ran fine for about 2 days then it started misfiring in cylender 3. changed the coil pack, still misfiring. then i changed the coil harness and stopped misfiring. drove it for about 3 hours and started misfiring again.
1. coils are good
2. compression is good
3. harness is good (swapped it in my friends sr)

(also, boost spikes over 15 pounds.. started misfiring after it spiked)

anyone have any ideas ? please help

[Mikester]

Maybe all the misfiring fouled the plug(s).

If cleaning/changing plugs helps it, you may try verifying the timing is correct, all vac lines & ports are leak free... the other couplers etc. Sounds like that poor car has been beat down. GL!

[n33sanz]

How are the injectors? What kind of fuel pump are you running?

[andres_240sx]

255 fuel pump
Not sure what kind of injectors I'm thinking stocks. But not sure, they're red caps