As another source, I had my 4-cyl injectors cleaned at
www.cleaninjectors.com in Bitely, Michigan. Good turn-around, hardcopy report (which the cleanies around my house promptly pitched into the recycling the day before I went to file it) with before/after cleaning flow rates so you know whether to expect a change in behavior from the injectors, new pintle caps. Can't say anything special about it but that it really eased my mind about whether the injectors were a problem source. They weren't. $49 plus postage to the shop.
Greg Gordon's oldebottles.com page gives some detail about such things. Spica injetors are more like diesel injectors (high pressure), while the Bosch injectors are low-pressure jobs. Cleaning rates may differ on the two kinds. I didn't look it up. Greg's info really helped me home in on the actual problem when I thought I had various ones on an '86.
Michael