I recently bought a stock 89 gxl with 110,000 that someone put in a used motor. It ran and sounded good but never idled. I took off the intake and found it had a bad gasket at the block. while it was apart i got the injectors refurbished and tested along new insulators and o rings. I checked the vacume lines and put it all back together with new fuel fiter ngk plugs and oil change. It idles a little better but still a rough 1500 rpm. The cold start still work at start up but then drops down to 1500. I tested the output of the fuel pump and got 70 psi. when i did a inline pressure test it only put out 45 psi but it held the pressure good. I need some more ideas please.

 

I am guilty for touching the screw on top of the throttlebody. I dont know if this contributes a whole lot to the idle

 

What is the condition of the spark plugs? And does it ever drop to 750 RPM once it warms up? 1500 RPM is only normal if the engine is cold.

45 psi of fuel pressure is actually a little bit high, if you tested with the fuel pressure regulator (FPR) vacuum line removed. It should be around 30psi at idle & about 40 psi at 0 manifold pressure (atmospheric).

And messing with the TPS can easily affect idle. http://howto.globalvicinity.com/gv_w...i=58&co=1&vi=1

 

when i tested the fuel pressure i had the yellow connector jumped. 70 psi with just the gauge hooked up. i got 45 psi with the guage hooked up inline after the fuel filter before the regulator. with the jumper taken out it read 38 motor running. sorry if im hard to follow.

 

I would figure out how to get the screw back to oem. That will cause you problems during the rest of your troubleshooting.