Fuel Pump Or Injector Problems?

recently I Bought A 1994 Chevrolet Astro, And It Was Shaky, I Thought That Maybe It Needed A New Fuel Filter Accomplanied By The Complete Tune-up, I Took It To My Mechanic And He Gave It A Complete Tune-up, When I Got There He Said That My Van Might Need An Injector From The Throttle Body Or It Might Need The Fuel Pump, Here Is What It Does, When I Turn On The Van It Doesnt Start Right Away And If It Does It So Shaky And Its Barely Gettin Enough Energy To Start Up, So What I Do Is I Turn The Key And Let It Sit For 5 Seconds Then I Turn It On And It Starts, But Its Still Shaky For Some Reason, And I Get The Scent Of Gasoline So I Dont Know If Its The Fuel Pump That Needs Replacing Or If Its The Throttle Body Injector, Ive Read On Alot Of Forum Boards That On These Vans That The Fuel Pump Is Usually The Problem, So I Was Trying To Get Some Advise And See What People Thought The Problem Might Be, Because The Throttle Body Injector Goes For $320 With The Installation Its Going To Be Close To $500, And I Think I Might Be Paying A Similiar Price If Its The Fuel Pump, So I Dont Want To Waste My Money On Somethin Its Not, So If Anybody Has Any Suggestions Of If They Have Gone Through Similiar Experiences If You Would Share Your Experience And How You Solved Your Problem, I Would Be Very Greatful, Thankyou

First thing is to check the fuel pressure and fuel pressure drop.
Is this a VIN "W" engine...vortec v6?
If so then most likely the CPI unit or the lines feeding it are leaking internally.

i checked my vin code and yes it is W and it is 6 cylinders, i asked my brother and he said if it was leaking fuel internally the engine oil wouldnt of been clean, and he thinks if it would of been leaking internally into the engine, the oil would of gotten thinner, and i would of probably of heard some knocking because the rockers wouldnt of gotten the needed lubrication they need, also gasoline ignites at 180 degrees and the van has been above that and to my knowledge it would of blown the engine, how would i go about checkin the fuel pressure and the fuel pressure drop, is that somethin that i can do or should i take it to a dealer or a mechanic, i thankyou for your time and patience and for your time taken to answer my questions

i checked my vin code and yes it is W and it is 6 cylinders, i asked my brother and he said if it was leaking fuel internally the engine oil wouldnt of been clean, and he thinks if it would of been leaking internally into the engine, the oil would of gotten thinner, and i would of probably of heard some knocking because the rockers wouldnt of gotten the needed lubrication they need, also gasoline ignites at 180 degrees and the van has been above that and to my knowledge it would of blown the engine, how would i go about checkin the fuel pressure and the fuel pressure drop, is that somethin that i can do or should i take it to a dealer or a mechanic, i thankyou for your time and patience and for your time taken to answer my questions

Is your brother a automotive technician?
Also since gasoline is considered flammable, it gives off sufficent vapors to burn well below 100 degrees, it must have sufficent oxygen and an ignition source to readily burn, to explode, it must be within its upper and lower explosive limits....what else do you want to know about Flammable liquids and gases, haz-mat or fire suppression?
Now back to our discussion...the CPI unit in these trucks have been known to leak causing hard start, rough running and black smoke from the tailpipe complaints.
The CPI is housed in the lower intake manifold with the upper bolted on top, this creates the plenum....the fuel is injected at the intake runner in the head by a nozzle...air comes in the throttle body and is directed by the plenum......no fuel is supposed to get in the plenum.....when the CPI unit leaks, raw fuel is introduced into the plenum causing a rich condition....the result is the complaints I mentioned before.
There is a shrader valve on the fuel line at the rear of the engine, you will have to remove the engine cover to access the valve. Install a fuel pressure guage and turn the key on.. does the fuel pressure go to about 55 psi and hold steady or is it slow to rise and falls back down after a few seconds? If so, most likely the CPI unit is leaking.

thanks for the information, and no my brothers not a auto technicial hes a locomotive diesel technician but hes hard to get information out of so i came on this board to get information, i thank you for your information, and yes i have noticed some black smoke out of the tailpipe, thanks

thanks alot my problem was fixed, i took it to a new mechanic and he used a diagnostics machine and he found out it was a faulty throttle body injector, while he was removing it and replacing it with the new product he came across a leaked fuel line and another fuel line that looked as if it was ready to start leaking, so he replaced the injector and the fuel lines and now my van is starting automatically and it doesnt shake anymore, thankyou kind sir for your useful information, peace