Need some help. I have an 89 305 with TBI. I've had a rough idle problem I've been trying to fix. I decided to check the timing. So when I disconnect the est wire, the car won't idle. it will start surging from 1500 rpm and catch itself just before stalling. It does that on repeat. Pretty sure it should be steady even with thag wire disconnected. With the est wire connected, car runs and drives fine other than the rough idle.

Don't know what can be causing that. Car has new cap,rotor, plugs and wires. Also changed o2 sensor.

Any ideas? Thanks.

 

Have you tried keeping your foot on it, till it normalizes the idle? I used to have to do that with my 84. After some seconds it would idle normal, but it was carbureted. Worth a try.

 

Did you check the wear on the distributor gear?

 

Any vacuum leaks??