1999 Ford Ranger running rich

Have you checked for a vacuum leak any where pass the MAF sensor? A lean condition will cause the computer to enrichen the air fuel mixture. Vacuum leaks are common on these especaily on the intake tube and intake gaskets. Let me know what you find. TY

yes i have checked for vacuum leaks, no leaks.

Do you access to a scan tool that can read datastream (what the computer sees from the input sensors)?

yes a snapon scanner. forgot to tell you no cil, no codes, scanner shows every thing fine, it doesn't even show rich mixture.

A few things to check. What are the short term fuel trims and long term fuel trim at idle and 1500RPM?
What is the throttle positioning sensor read at idle and 1500RPM.
At idle can you kill the engine just by cranking the steering wheel (vehicle not in motion)?
What happens when you turn on the a/c does the engine RPMs increase or does it cause the engine to stall.
I forgot to ask if the engine stalls when driving or at idle? Does the engine stall more frequently when it is cold or at operating temperature? Answer these questions and get back to me, TY

i'll have to get the scanner back from my brother. I forgot to tell you, I changed the temp sending unit. I'll get back to you.

Ok let me know

finally getting back to you. fuel pump stopped working put new pump, pressure regulator and guage in, didn;t fix it. ac doesn't effect idle, idles ok. turning steering wheel doesn't effect idle. sft fuel trim at idle 6 to 12 lft 0to 3 1500 rpm sft 0to11 lft 3to11. tps v idle .77 1500 .92 engine shakes at 1500 ,short plugs out, can't find one not firing. unplug one coil pack,runs the same unplug other, runs same unplug maf senser runs same.mechanic for 40 years never seen anything like this.

Have you checked the throttle body for build up around the throttle plate. build-up can cause a air restriction when the throttle plate closes causing the engine to stall. Clean the throttle body with a rag and appropriate intake clean designed for throttle bodies (the throttle plates are coated so brake clean for example will strip that coating off). Try this and get back to me.