Hello guys, I am looking for some help and guidance on what to do here.
I have a 1995 impala ss, LT1 350/4l60e with some mods done to it. I am having problems while driving the car. It is lurching, stalling, surging, and the transmission is grinding a little bit. So far, I have done the following

Transmission filter change - dropped the pan and changed filter and gasket
Plugs
Wires
Throttle position sensor
EGR Valve
Fuel Filter
Thermostat (180 still)
Wiper Motor
Ignition Control Module
Ignition Coil Pack
Cap and Rotor
Distributor
MAF
Brake Pads
Starter
Alternator
Water Pump
Blower Motor
Water Temp Sensor
valve cover gaskets
o2 sensors
and Fuel pump(supposedly by last owner)

Mods that would have to do with engine/transmission
LT4 intake manifold
comp cam 1.5 rockers, springs, and rod set
3000 or 3200 stall,
52mm throttle body
K&N FIPK intake

On a side note, the car has power going to the gauge cluster, but none coming out, so I have a loss of speedo, odometer and blower motor. It was driving fine at one point while this electrical problem happened. I swapped the gauge cluster for one I knew worked and that didn't solve the problem either. any suggestions on that would be a bonus.

I have no idea what it could be at this point. Any other ideas would be very helpful, as I am about to ghost ride it into a wall at 60mph.


Thank you,
Alex

Edit: just changed the idle air control valve, it helped a little, but not much.
Edit 2: got a fuel pressure gauge - primed i am at 47psi, engine on and idling at 42psi, and while revving at 42psi.

 

went to pull it out of the driveway, studdering in reverse, eventually cut itself off, studdering when i went to pull it back into the driveway.