Used TBI units for a 4.3 go for about 30 on ebay, if the injector is hosed, it would be alot cheaper than buying new injectors.
Also, have you replaced the EGR valve? those have a tendancy to get funky over time, and will stick open, making it idle like crap.
If he has a wad of cash to blow, you can get a new bolt on holley unit with injectors for about 400 from summit or jegs.