Help diagnosing problem

[SayHiToRambo]

08 trooper 1100

Bit of background. First the machine would take for ever to start. So I adjusted the valve shims into spec and made sure the timing is correct. Starts perfectly now. 
 

now it fluctuates on idle. Bogs down, Revs up, repeat. I noticed the fuel pressure drops from 60psi to 20psi while that happens. It also bogs down at the lower end of each gear, higher rpm seems to be fine. Seems to struggle under load. In neutral it revs up perfectly. 
 

brand new fuel pump, fuel filter, gas. I noticed on the fuel pressure regulator there’s that vacuum nipple, it’s not attached to anything and I’m not sure where it would go. Possibly the problem? 
 

Another issue is the tip off the end of the exhaust is broken off, sensor is still attached and connected. Could that cause these issues? 
 

my next plan was to look into the pressure regulator and voltage to fuel pump while driving. Is there anything I’m missing or any ideas you guys have? 
 

thanks! 

[Dan B]

Difficult to troubleshoot remotely.  Things I might check.  Take a look at the ignition system.  When an engine is under load, the ignition system can breakdown.  The fuel pressure dropping to 20psi makes me wonder why.  It's an elecric pump and unless the voltage drops, it should maintain 50psi per the specs.  That port may be a port to measure fuel rail pressure.  But you could have a vacuum leak in the iintake manifold or the ductwork to the air filter.

[SayHiToRambo]

9 hours ago, Dan B said:

Difficult to troubleshoot remotely.  Things I might check.  Take a look at the ignition system.  When an engine is under load, the ignition system can breakdown.  The fuel pressure dropping to 20psi makes me wonder why.  It's an elecric pump and unless the voltage drops, it should maintain 50psi per the specs.  That port may be a port to measure fuel rail pressure.  But you could have a vacuum leak in the iintake manifold or the ductwork to the air filter.

Update. Fuel pump is good, no voltage drop. I removed the cat thinking it was plugged. Almost completely solved the bogging issue. 
 

I cleaned out the fuel pressure regulator. No abnormalities. Machine has fire coming out the exhaust when full throttle. Must be running lean. I upped the fuel pressure to 75psi from 60psi and it ran even better, flames out the back were noticeably less. Can’t adjust the regulator any higher. 
 

im thinking new injectors. 
 

anyone agree or have other ideas? 
 

thanks!