89 Starting Problems

My 89 Firebird has problems starting. When I turn it over it will just turn and turn until around 20 lbs of pressure on the oil gauge before the fuel pump kicks in. Then sometimes it takes 3 or 4 tries before the pump kicks in. I have replaced the fuel pump and screen, the oil pressure sensor, the oil check valve, various other sensors, and even the starter, alternator, battery and the distributor. I have had my keys checked and the VATS disabled with no avail. It still has the same problem. What should I do next? Now we are discussing replacing the distributor with an HEI vacuum advance and the intake manifold so we can put on a regular 4bbl carb and hot wiring the fuel pump. Would this be the best plan of action?

My 89 Formula was having starting problems also. The starter and engine turned, but it was as if the car didn't have any gas in it.
With the engine running, we sprayed carb cleaner directly into the throttle body while the accelerator was pressed to open the flaps. The car choked and sputtered and died a few times, but then a huge cloud of white smoke blasted out of the rear pipes. That took care of it. Apparently the fuel system was filthy, I guess.
Then I filled up with 93 octane and put 2 of those 104+ octane boosters in also. I was told to use the black bottles. Car runs ALOT better now. Better pickup, and more powerful burnouts!

While we're on this subject. My 89 does much the same thing but the problem goes beyond the fuel system. Seem I have a wiring problem with power to the ecm. The car will start up and the check engine light stays on. Put the car in gear and drive about 100 feet give or take and the car stalls. Try to run diagnostic but the light doesn't come on car won't restart for several days. Try diagnostic again and flashes all good (code 12). Have replaced the ecm twice in the last year, disabled the vats system, and have checked both spark and fuel pressure ( 38psi running). Car has 191,000 miles. My last guess is the wiring is shorting out or bad ground.