Idle problem

I have replaced the tps and iac checked all vacuum replaced distributor but when I set the timing according to the manual the my fiero still idles high even after the IAC resets. I then rejumper to check the timing and it is not at 10 degrees BTDC any more. I have tryied to just set timing by the tach also at 1000 rpm this does the same thing. What is causing this? Help please The car is still coding 21 and Why is my timing light showing different after setting right ?

Maybe a little more info on the car before you are going to get help?

 

Is the car a V6 or a 4cyl. 

More importantly, does it look like the wiring has been tampered with.  I have seen cars with household lamp wiring used for grounds and garden hose for heater hose.

To set the timing correctly on a V6, get the car up to operating temp.  Jump the A/B terminal on the ECM and leave it jumperd.

Now go back and check adjust and set the timing.  Note as you crank down the dist hold down bolt you will lose a couple degree's of timing, so I always tell people to set it for 12 and then tighten it down. 

Now go and remove your jumper.

Car should idle around 1000rpms give or take 200 for tach error in either direction.

Shut care off and disconnect battery, or remove ECM fuse for at least 30 seconds. 

Fire car back up, if it still sets a code 21, you have a wiring issue or a defective TPS.  Seeing as you said you already replaced the TPS, I would suspect wiring.

ECM needs to see .5 volts idle and 5.0V at wide open.  Give or take .25v at wide open and .10v at closed.

I would start checking grounds ALL the grounds. 1st ground to check is Engine to chassie.  Should be a braided strap in the passenger side bulkhead area.  If you can't find it, replace it.  Go between the engine and the trunk hinge.

Check the grounds on the driver side, head closest to the bulkhead wall.  Are the grounds still there.  If they are clean them and re-install.  I believe there is 3 or 4 wires on 2 ringed connectors. 

Now check the battery to chassie, should be a black wire from the battery to the frame near the battery post.  If its missing or dirty, make a new one.

Next go inside the car, remove the center console/glove box, there should be a ground from the ECM harness to the frame.  Clean it.  Its held on with 1 7mm screw.

If after all this, it still don't work right,