1995 AUDI 90 CS - Hard to start... spark & fuel OK

Wouldn't be the timing belt. Could be the idle controls, or the MAF sensor, or a dirty air or fuel filter.
Be sure and check for trouble codes. Pull the spark plugs and check their look and the plug gap. A cylinder that is firing good (good compression, good air/fuel mixture, good ignition) will have a tan or gray look with very little deposits. A lot of black, sooty deposits indicates running rich, a blistered, white pug indicates running lean. And black, wet deposits indicates oil fouling from worn rings, most likely. Check your plugs, probably good, but see if they need replacing.

clean up your fuel system and chek your ignition

replace the alternator,this is the problem,please rate thank you.

First off, I think you bought a raft of stuff you didn't need on that repair job! The sound of it at this time is that probably the fuel pump is about gone.You need to measure the fuel pressure (engine running) at the fuel rail (the test port looks like a tire valve) above the injectors. The pressure should be in the 45 to 55 PSI range. If the pump is toast, it will be much lower. The pump resides in the fuel tank. You probably have the check engine light on. If the code(s) are read out with a scanner, it will likely point to the fuel pump.

key may need reprogrammed

Seems that the fuel pump quit, check for fuel pressure, check for spark in the plugs and the fuel filter.

gas into the carb doesn't work all that well.... hard to regulate it for one thing.

this year model is notorious for fuel related probs...check the remainder of the fuel system, injectors, and the fuel pressure regulator also verify that the fuel pump is actually running and getting the correct amount of power to the pump itself..... it may not be bad just not getting enough power

replace the distributor oil is leaking into the electronics of the distributor and shorting out pull cap back off and look and see if oil is leaking out

spark plugs known problem when cold