Stop guessing. Replacing sensors is stupid. Most OEM sensors at 20+ years old are better than new Chinese crap.
Did you set "minimum air"? If you rebuilt the motor, it is very likely that is an issue.
How 'computerized' is the engine ?? Running rich in a computer engine is usually an O2 sensor fault.
Year, make, model, engine size, mileage...and I promise you'll get a good answer, otherwise not likely.
The EGR could cause the stalling, pull it off and see if it has something stuck in the pintle. The sluggishness makes me think though that you haven't got the timing set correctly, has that been done properly? Also, GM MAF sensors of that vintage can have problems, do you have another you could try?
Also, It would really help to have the model, is it an astro van, what's the 8th digit of the VIN????????????????????????
It is a 93 chevy V6 4.3L. It has 206000 miles on it before rebuild.
Once it levels out it sounds good. It is sluggish when you give it gas. When you come to a stop it dies. It is also running rich. Could that be the EGR valve.
