My customer reported to me that the EFI light is on and the engine is running very poor with foul smelling exhaust. I reviewed my Toyota manual and found a list of engine codes. there is a four prong female plug right by the ecm I assume for diagnostics. Is there a way to get the EFI light to flash me a code to further my troubleshooting?

Have you performed vacuum test

I have mainly lp trucks but they are known for sludge build up in the throttle body. It can hang up the throttle plate creating issues. Loosing up the throttle body will allow better air intake and give you a different reading. You also should disconnect the gray and green connectors on the relays.

no I have not cleaned the throttle body and no I did not loosen the throttle body during the compression check how would have that affected the compression check may I ask and would a dirty throttle body be a possible cause to the issue that I am having thanks for the help.

Have you cleaned out the throttle body? When you did your compression check did you loosen up the throttle body?

4Y engine has hydraulic lifters, no valve lash adjustment.

Compression was checked with engine hot. I did not sqirt oil in the cylinders but I would have to try to see if that ups the compression. I have not checked valve lash but could check that as well. Thanks for the suggestions.

When you did your compression test did you do it with engine cold or at operating temp? Did you do a second test with a few squirts of oil in each cylinder and retest?? If the manual is stating 122 minimum and you are getting only 110 then it is low on compression and could be a part of your issue.....have tou checked and adjusted your valve lash??????

No the truck is gasoline only no propane. It starts decent at start up but after it starts if you run it no longer than 5-6 minutes and shut it off it acts up(as described above) but if it runs up to operating temperature it starts fine with no problems and during this time there is no check engine light.

Is it dual fuel?
You may have an injector stuck open, flooding the engine warm.

Thanks for the info, it was insiteful however I forgot to mention this motor is a electronic fuel injected motor completely drive by wire electronic motor any ideas?

Since it's gasoline, it changes the normal diag of a propane fueled engine. Sounds exactly like any old chevy from the 80's with carburetor. Guy would start the car cold, then go for cigarettes around the block. The engine started fine cold, and had enough heat for a restart WITHOUT the choke. But when he got back in the car a few minutes later, the choke came back on full and flooded the engine....if he touched the accel even slightly while cranking. The only way you could do a warm restart was to floor the gas pedal. The car started but smoked and ran rough til it cleared. But you never had an issue if the car reached operating temp.
Youre choke system may have lost power to it's internal heater. Check that first. Make sure the linkage is opening the choke when the gas pedal is fully depressed. Usually the choke cant close unless you open the throttle a bit but some carbs did not have that feature. You may be running rich or worse have a buildup of carbon in the manifold. Last one I did had an inch of carbon under the carb!
If you dont want to spend much more time, just make sure the operator doesnt touch the gas on warm restart and floor the pedal if it doesnt start right away.