Hello, I'm new to the site and need some help. I bought a 87 TA 305 TPI and have some issues. ECM shows no codes except 12. Running very rich and idle is up and down between 2000 & 1000 in neutral. No voltage at TPS at any time. Engine idles and runs good with IAS unhooked. Have tried the adjustment, doesn't help. Engine stays revved for a few seconds when press gas pedal and let off. Idle in Drive fluctuates around 600 to 1000 rpm. Where do I start?????!!!! Please help!!!!

 

First of all, the 1-2 from the ECM says that the ECM is functioning OK, but maybe not. You should have voltage at the TPS with the key on. If you dont, you must find out way, wiring issue?, ground issue? The TPS has three wires, labeled A, B, and C. I think the power supply is 5V and its should show up between wires A & C, I think. And as the TB opens slowlt, the voltage between A & B should slowly rise. Go to the tech article page and check this out.
And for the IAS, I think you mean IAC, idle air control. These get dirty and get old and slow to respond.
Plus, if the ECM hunts for idle, many times its a vacuum leak at the runners or other. Or its a bad IAC motor.