[DieselSJ]

You think 10mpg is bad for that truck? A 1-ton 4 wheel drive dump truck? That is a lot of truck for a stock TBI 350. You really won't do much better than 9-10.

OK, with the engine running, point your timing light at the bottom of the injectors. You should see a nice even cone pattern with no dripping. Also, reman injectors for those are garbage. For not much more $$ you can get new. Also are you sure you got injectors for a small block and not for a big block? It is easy to screw up the o-rings around the injectors and they will leak.

You said fuel pressure is "good". What is the actual PSI and where did you measure it?

Check engine light on? Failed sensor will almost always trip a CEL. If you are as rich as you say then it should trigger a CEL for that.

Make sure you got the correct EGR. I know for my 87 there are 2 versions and they operate differently and they are not interchangeable.