Engine Hesitation?

Wow, you've thrown a lot of stuff at this thing.

Surging idles can be a nightmare to solve.

A few more things to check out.

If you have a slight vacuum leak, the ECM keeps trying to control the idle with the IAC, but it doesn't respond like it's supposed to, so the ECM keeps adjusting it back and forth.

I know this will sound crazy, but sometimes cleaning where the ground wires attach to the engine helps.

Might check the fuel pressure to see if it is staying steady.

And on rare occasion, even though you should never have to do it, I have adjusted the throttle plate stop screw a little one way or the other and that seemed to help it.

Sometimes there is just no silver bullet for idle problems.

If you unplug the IAC, does the idle stay steady?

Can you do a fuel pressure test and blip the throttle a few times. The pressure should go up just for a second or two when you open the throttle and the vacuum goes down.

This has the BI unit on it which they liked to blow the gasket under TBI sometimes computer will mix fuel higher to compensate other times not check that by pulling TBI off. Also, if any vacuum hose is soft replace it especially to MAP sensor on firewall. Check fuel pressure as well but you will need an adapter for that 9-11 psi.