engine has slight surge after timing. idles at 650-700 rpm then surges t about 1000rpm then back to normal. what's the problem?

 

Surging after you reset the timing?

 

yes. engine idles around 750 - 800 rpm cold but surges to 1000 rpm at warm/hot idle. up and down between 750 - 1000 rpm.

 

surges are typically vac leaks. Odd it appears after timing verification...

 

Did you disconnect the EST when you set the timing?

 

any updates?

 

Could be a dribbling injector, sometimes as the injectors age they will dribble a little fuel at low speeds (idle), and as the engine picks up the excess fuel it surges. As mentioned it could also be an air leak somewhere, take a propane torch and gomaround the upper and lower intake seam, base of the lower manifold etc, if the engine revs up anywhere you know what gasket needs to be replaced.

You can try dialing up the fuel pressure a bit, this sometimes can be a bandaid fix for dribbling injectors. Check the PCV valve too