2G multiple codes for cylinder 3

[streetenvy]

Need some help lately my 98 Gsx has been running rough and idling horribly the following codes (2)p1105 fuel pressure up solenoid p0300 random misfire and p0203 injector circuit open ... Spark plugs has been replace injector 3 has been replaced the car runs like crap then snaps out of it and drives fine on and off again really need help

 

[boost97gst]

Turn the ignition on. Check both leads of injector 3 clip. They should both have +12vdc(or thereabouts). See what you find.
The ecu grounds one side of the coil in the injector to open it. SO, if its saying an open you probably have a broken wire. Which is "floating", not ground, nor power.
Go from there and see whats up

Edit: Wiggle the wires all over as you trace em back while you test. Sounds like vibration and a bad connection. Could be at the resistor pack or the side that runs to the ecu.

 

[boost97gst]

Whats the word? Any luck?