You may want to (if you haven't yet) clean the MAF elements with contact or carburetor cleaner. After which, you may want to check fuel pressure engine idling and while the engine is under partial load conditions.
If you have access to a scanner capable of monitoring system PID's using the datastream option, it would be helpful to check the short and long term STFT and LTFT values while the car is under partial load. LUK
LUK=Let Us Know, GL=Good Luck, LMK=Let Me Know, JIC=Just In Case, BTSTDTRT=Been There Seen That Done That Repaired That, YCYDYP=Your Car Your Dough Your Prerogative and the classic... DILLIGAS=Do I Look Like I Give A S***
1986 GT-X303 cam, 289 heads, 1.72, Holley 700cfm DP, RG 4+1 Trans