Hi guys,

First off, I am not a mechanic so I'm just trying to understand why my 73 2.0 is hesitating and surging through the gears. I just had the motor rebuilt to 2056 with 96mm p/c. We kept the stock FI and cam. It was running great with more power but the idle was high. My mechanic said the throttle body is worn out and leaking air causing the high idle speed. I wanted to get the idle down to 1000-1200 from the 1400-1600 and he pulled the timing down to get the idle down. After that it has been hesitating and surging worse and worse. Even after advancing the timing again it's running poorly.
My question is if the throttle body is worn can it be replaced or just cleaned? Is there anything else you might recommend I tell my mechanic? I appreciate any advice given!

Sounds like a air/vacuum leak. Check around the intake plenum, they tend to crack around the mounting tubes, usually on the underside.

Spray some accelerator around that area while the engine is idling.

Thanks Andy! Will do.

I would suggest checking on the distributor as well. Is it the original? Is the retard and advance hooked up correctly?

It is a new distributor and has a Pertronix pointless ignition. Not sure about the retard and advance being hooked up correctly but I would think so as it ran so well when I got it back right after the rebuild.

I chased this problem for months. Mind was cured with a new Throttle Position Sensor. You can buy a new circuit board and rebuild you existing TPS and that usually fixes the problem. My TPS however was to too worn and the circuit board replacement did not cure the problem for me. I ended up finding a NOS TPS and that did the trick. These are almost impossible to find and expensive when you do. Try rebuilding yours first in most cases that works to solve the surging/hesitation.

Just disconnect the tps and see if the behavior changes. A normally running Car runs fine without it.

Thanks guys. I'm going to definitely do this!