Just did a thorough cleaning of the entire intake system on my newly acquired '89 740tic.

For you I'd recommend removing the intake manifold and replacing the gasket. You'll rule out any air leaks that way. You can also take the entire intake body to a shop for cleaning (about $25)

Buy new injector seal kits. You'll need just two of the three rubber o-rings and SAVE your original spacers. I believe the spacers in the kits are too thick. forget about trying to save the plastic caps on the ends of the injectors. They will break when you remove them. I used an adjustable pliers to remove mine, yet I think I still needed to pry them off somehow. Maybe catch the rim on a sharp edge of something and pull down on the injector body so the cap comes off like a bottle cap.

The replacement caps are a press-fit. I just pointed the injector doen onto a hard surface and presser on the caps. (Of course, you don't want to hurt the pintel) Lube the o-rings with a little silicone spray for reassembly into the intake body.

Read up on the procedure in the FAQ

replacing the control pressure regulator on my 85 turbo was a pain. Actually it was not too bad but I had to take off the intake manifold and that was a pain. other than that it is easy. Just disconnect the fuel lines, unbolt it and then install the new one. I got a good used one from someone on the brick board for $40 shipped. I replaced mine and found out that the old one worked fine. So now I have an extra and if it fits your car then I would be happy to sell it to you. Otherwise they are hard to find and a new one ranges from $250-350. Also check the local salvage yards, or post something on the brickboard asking if anyone has an extra woking one. Thats what I did. :)

Charles 1985 245ti 134K

Well if it's anything like on my '85 Turbo (different K-jet, but still a k-jet) the injector seals were really easy and seated just fine with the new ones. I didn't replace the FPR, did rebuild it though which may have helped (or something else I did helped, I'm not sure). The injector seals should be like $5 or less for all of them. The FPR (I looked into replacing) was very expensive, some hundreds.
HTH