just wondering if anyone can help with this. my 90 has fuel injection. the pressure is supposed to be 42-47 punds. i have checked it and it was 42.  i know when you run it there may be a slight drop in pressure for a second . anyone know what the limit is for the drop in pressure? basically i am trying to determine if i have a weak pressure regulator. i have recently installed a new fuel pump. thanks for any help.

Did you check the pressure with the vac. line connected to the regulator? That is "normal" pressure, or "idle" pressure. If you disconnect the vac. line from the regulator, the pressure should go to "Max". If it does not, the regulator is prolly stuck, or bad.
Also, check the pressure with it running, not just sitting with the key on.
Some regulators can burst the vac. diaphragm in them, and you'll wind up sucking fuel up thru the vac. line into the intake, making the engine run a bit rich.
I know my '85 pressures are not that high, but the later cars do run at a higher psi, and use higher flow-rated infectors.
If you do find you have to replace the regulator, go with the adjustable one. Then you can fine-tune the pressure to match the infectors, and the needs of the engine.

i didn't disconnect the vac line when i checked it.  will try that though.  and checked with the engine running. i ran a can of the pro type injector cleaner thru the lines and it feels it has better response now. still has a slight unsteady idle.  i am thinking that my regulator might be on the weak side as the pressure is on the low end. guess i will hook up the pressure guage and run and if it drops below the 42 i will replace regulator. i would hope that an adjustable regulator would be just the cover and diaphram to replace and not the whole body. i know you can get just a new diaphram for the one thats in there.