Why won't my car start normally?

When I start my car (1994 Chevy Beretta 2.2l) after it sits for more than 4 hours it idles really bad abd occasionally stalls within the first minute of running... after the first minute it runs perfectly. I have replaced the spark plugs and wires fuel pump and filter and had injectors cleaned. No vacuum leaks found and no engine codes. Help!?!?