TBI running rich...Help!!

[DuckAholic1]

Any suggestions? 87 5.7 TBI rinning rich! Looked for vacuum leaks, none found. Timing set perfect. Spray from injecters look good(no dripping). Recent Throttlebody rebuild. What am I missing? Need your knowledge!!! Thank you!!

[SLUG]

I would check O2 sensor. Do you still have factory exhaust?

[DuckAholic1]

Flow master exhaust. No headers.

[78BIG-TEN]

Check vacuum leak or the vacuum line from back of tb to map sensor or possible bad map

[DnStClr]

Your troubleshooting can be made easier by looking for codes thrown by the ecm. Did you check for codes? As suggested by slug, the O2 sensor is a possibility and so is the throttle position sensor, coolant temp sensor, timing too advanced, ===all kinds of possibilities.
check them codes.

[Irish_Alley]

cts is a good start i did a write up about how to test them
TBI sensors and testing
Obd1 code retrieval and decoding
1987 manual
1973-87(91) GM Pickup Manuals

[Captkaos]

Get the codes and posted them or look at Irish's posts and follow them.

[DuckAholic1]

Thanks everyone, will be checking codes in the A.M.  Will post what I find. Wish me luck concidering it's my first time doing such!

[DnStClr]

You rebuilt the throttle body- did the kit include a new fuel pressure regulator? A weak spring there can be a cause of too much fuel.