I would not bother installing those Amazon injectors if you gave them to me. They might be fine, but that's not a part I'm willing to gamble on. If those Precision Auto injectors are actual Bosch units they should serve you well. What has prompted you to replace them?
The fuel pressure regulator you want is FP10021. Don't trust retailers' compatibility lists - most of them are wrong. Get that part number. Why do you want to replace the FPR?
Be careful with the injector rail. It's not available new from anyone at any price.
Agreed, chance of getting bogus parts off amazon is non-trivial.
I say if you're in there doing injectors, go ahead and do the regulator, because the upper intake has to come off to do either job. Also be sure to replace the vacuum line to the regulator and be sure the hose is fuel-rated. Regular vacuum line will deteriorate quickly in that application and then you're removing the intake again to replace a little piece of hose.
How many miles are on the engine? If it's around 150K or more, you better just go ahead and check that distributor for wear and be prepared to replace it. Turn the rotor back and forth and as you do, try pushing it side to side, checking for wear in the upper bushing. Read up on setting the cam retard angle and what scan tools are capable of this reading, as well as marking both distributor body and rotor position, before pulling the old one.
"Be careful with the injector rail. It's not available new from anyone at any price."
This cannot be overstated! It's plastic, the plastic will be brittle, and no matter how careful you are, it's possible to break the little nubs that the injector retainer clips attach to. So treat it like it's made of glass, and still be prepared to patch it back together. I had success using small flat screwdrivers to carefully release the tabs, still managed to crack a couple. Used zipties looped through the injector clips to hold them in place on re-install. It's not the easiest to see in the pic but they're not just looped around the clip; they're looped through it so that it sits in its natural position.
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Another piece of total unobtainium is the EGR tube. It's easy to damage it on removal because the fitting into the intake has a very shallow set of flats that are difficult to grab with a regular wrench. So you go to turn the coupling nut on the tube, and often it will twist the entire tube and destroy it. I strongly recommend get a SKINNY adjustable wrench - ChannelLock makes some - as a backup wrench on the fitting, then use the two-wrench method to break the coupling nut loose. A scrap of 2x4 against the valve cover was used to keep the backup wrench from moving, or damaging the cover.
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Richard