94 5.0. Upgraded inj and maf waay too rich

What are you doing to tune the car? If binary editor, did you plug in the supplied values from pro m for the maf? Also did you adjust both your high and low injector slopes and injector offset? All of these need to be set correctly for the car to adjust for the changes made.

That would be your problem. When you install new injectors they need to be calibrated to your MAF. Without a tune you have no way of doing this. The pro m sensors are meant to be big so that they can always be set to match the injectors in the tuning. Going to something like lightning injectors and a lighting maf might be an option but let someone else verify that as I'm not 100% sure. Imo your best bet would be to pull the pro m stuff out and the new injecotrs and put the old stuff back in and buy an adjustable fuel pressure regulator. By increasing fuel pressure, you effectively make your injectors act bigger. You could put one of those in and ditch the vortech regulator and be much better off. If you don't have one already, a wideband is important for this kind of stuff that way you can make adjustments off your afr instead of guessing

First of a what is all done to the car? I also didn't realize that pro m calibrated to the injectors and most times the advertised flow of an injector won't be it's real world flow. That's something that you find to be very true when you change injectors and need to tune the computer for it. Is the maf a blow through or a pull through? The iac could be the stalling problem but I don't think it would make the car run super rich. The rich problem is due to not having a tune. The stock rail has no problem with the pressure increase. When. I put my car together in the very beginning it was a 302 with a vortech and I ran stock injectors with the pressure turned up. I assume since you're talking about the vortech fmu you have one of their blowers correct? As far as pressure I'd have to see if I have it written down somewhere. I know an old engine builder friend of mine gave me a formula for figuring it out I'll have to see if I still have it. A wideband o2 sensor is a O2 sensor that goes in your exhaust pipe and tells you the amount of unburnt fuel exiting the exhaust. Any supercharged or turbo application should really have one. With one it allows you to see what your air fuel ratio is. So when your car was running lean it would have been giving you a high reading, something in probably 16-17 range. Now that your car is running supper rich it would give you a low reading something probably in the 10 range or lower if you're having problems fowling plugs. If you instead one of those it would allow you to fine tune the amount of fuel the engine needs to make max power while being safe (12.8 is Max power on a supercharged application). My suggestion to you as mentioned earlier is to pull the new injectors and maf out, put the old stuff in, install a wideband and adjustable fuel pressure regulator then fine tune your fueling till you can get a quarterhorse and binary editor. After the windeband and fpr are in you would just adjust your fuel pressure to get the afr correct. More fuel pressure = more fuel going into the engine and visa versa.

I know nothing of your FMU / Supercharger configuration but years ago I bought the PRO-M calibrated MAF along with a set of injectors and it ran pig-rich as well. You can tune the car of course, which I intended to eventually do (and eventually did), but in the short-term dropping the fuel pressure via an adjustable fuel pressure regulator made it run reasonbly well.