Serious answers or thoughts only please!!!
my 1992 305 tbi feels like it's running out of fuel down low in Rpm's, 1st gear is fine then in 2nd it'll slug until about 50mph and pick up power really hard and does the same through 3rd and 4th, also something to mention that might be important is as soon as it shift it shoots a huge black cloud out of the exhaust but I already know my valve stem seals are SHOT!!! Please help me out anyway you can

 

Connect a scan tool, look at the data stream while someone else drives the vehicle. Connect a fuel pressure gauge, look at fuel pressure as they're driving and the vehicle is acting-up. Perform a cranking compression test. Buy a spark tester for HEI ignitions--or an adjustable spark tester--and verify that the ignition coil isn't weak.

I'd want to know O2 voltage and cross-counts, short- and long-term fuel trim, coolant temperature, knock sensor activity, and anything else that looks suspicious.

Is there anything left of the catalytic converter? Original? Gutted/removed?

If the valve stem seals are that bad, the plugs might be fouled and the chambers filled with deposits. Oil in the air/fuel mix lowers the octane rating of the fuel, and the deposits can raise compression. Both lead to detonation, detonation leads to knock sensor going crazy, and that leads to retarded timing and poor power. Look at the plugs when you have them out to perform the cranking compression test.

 

 

Its a truck, and the only place to plug in for checking pressure on a TBI is under the drivers seat along the frame with an adapter between the tank and the fuel filter, so lol please dont drive down the road, door open looking down at the pressure.

 

I use This adapter , and plug it directly behind truck tbi, and just put gauge under windshield wiper to hold it down.

 

That's the advantage of having a long hose. Allows the gauge in the cab while the adapter is in place near the fuel filter or by the throttle body. I found it impossible to connect my pressure adapter on a van--there was no room behind the throttle body assembly. Had to use the adapter that fits in place of the fuel filter.