It does sound like it is running lean. The computer is supposed to do the fuel mixture adjustments to keep it running right. If there is a vacuum leak or a fuel system problem, the computer cannot keep up with the demand.
One simple test you can do is to remove the air filter cover to expose the inlet(top) to the TBI. Start the engine and hold an UN-LIT propane torch nozzle over the top of the TBI. If the engine runs better from drawing in the propane, it is not getting enough fuel, it is getting too much air, or the gasoline is bad. Not enough fuel could be fuel pump, fuel filters, fuel pressure regulator, or fuel injectors. Too much air could be EGR valve stuck open, vacuum hose leak, or intake manifold leak.
These causes are assuming that the fuel injection system is working properly. If the computer is bad, a sensor is bad, wiring is bad, or a bad injector, you could get the same results.
In the past, I have had problems with an EGR valve(1990 454). It is located on top of the engine, under the air cleaner housing, right next to the TBI. It is about 4 inches round and has a vacuum hose hooked up to it. If you reach your fingers around to the underside of the EGR, you can pull up on the diaphragm to unseat the valve. Do this right after you start the engine, the engine will die, but any carbon stuck in the valve should clear out. It is a simple FREE test that can possibly fix your problem.
If not, look for other vacuum leaks first, then start on the fuel system.
