So this may be a little lengthy but I appreciate any help that comes my way.

I bought an 87 ranger a year ago from a private seller and at that time it was running fine but after a few months I started losing engine power to the point where second gear was my last one that I had enough power to stay in. Truck wouldn't go over 20mph. now the truck floods the engine and wont drive and idles super rough
work done:
throttle sensor
Inertia switch bypass
Fuel pumps
injectors
Regulator
Fuel lines
Spark plugs
Wires
Icm
Timing chain and gears
It's been re-timed
straight pipe exhaust so no cats
air filter
Map sensor

other information: previous owner had ripped out Fuel pump wires when offroading and now has a killswitch in cab. When the truck starts it idles rough as crap, turn off Fuel, evens out, idles high but doesn't shake like crazy, then before it dies turn on Fuel pump and it runs super rough again and may flood out.

 

Check fuel pressure, you can rent fuel pressure gauge or buy one they are not too expensive

30-40psi is spec with engine running
And with a new pump and regulator pressure should hold with key off(switch off) at 15-20psi, if injector(s) are leaking

Electric fuel pumps are capable of 80+psi, which is why they need a pressure regulator, "new" just means NEVER EVER TESTED, not it works
Check the vacuum hose on regulator, no gasoline should be present

And it could be a computer issue, open it up and look for leaking capacitors or any circuit board corrosion

 

Fuel pressure was tested and was good. I could pull the computer and see if it needs a replacement. Any other ideas friend?

 

What was the pressure?

 

38psi I believe. It's been like a month so I'm not exactly sure

 

And did it hold above 15psi with key off/switch off?
That would tell you if new injector was leaking

In Rangers fuel pressure should hold above 15psi for MONTHS and MONTHS, even over a YEAR

Each injector gets 12volts with key on, on the red wire
Other wire is a Ground from the computer, your 2.9l runs Batch Fire injection so there are only 2 ground wires from computer, each opens 3 injectors every other RPM
Odd and Even, so 1 3 5, then next RPM 2 4 6 open
With key on engine off put volt meter/test light on battery positive and other probe on injector Ground wire, the not red wire, should see 0 volt, test one odd and one even cylinders injector

 

That I don't remember. But I can surely retest. I'll let you know

 

Retested the pressure. 40 psi engine off switch on. 37 psi engine running. Pressure never dropped when turning the engine off. But I did lose like 3psi from the 40 when I turned the switch off after having it on to reread it

 

And did it hold, all off, after 5 minutes or so?

 

It was like 15mins at least

 

Then injectors are all OK

 

So is it the computer then?

 

Looks like it
If it can't run the correct air/fuel mix and its sensors all seem to be working then the computer itself is now suspect
There is no way to test the computer, just test everything else and end up at the computer being the issue