Intermittent hesitation and RPM surge, no codes

First there was severe hesitation under load. Now hesitation seems to be less. But there is a rough idle. And rpm surging. Put it into reverse for example and the rpms increase significantly before going back down. These problems are only intermittent and there are never any trouble codes thrown. Check engine light comes on sometimes but does not stay on. I have put a scanner on it. Fuel trims seem fine. Except my scanner shows a couple of short term fuel trim listings beyond the two short and long term trims of both banks. I think these are listed as short term fuel trim bank 1. S2 and S3. And they both show a stable 99.3 percent. I take these are irrelevant for this vehicle? I have changed and cleaned the MAF sensor twice. Measured voltages with volt meter. Changed plug wires and plugs were changed last year. Changed Inlet air temperature sender. Checked battery connections. Alternator fine. EGR tests fine. Replaced map sensor. I did carburetor spray to check vacuum leaks. Nothing. When idling fine vacuum gauge is steady near 20 psi. I have a backup idle air control sensor and cam position sensor and coolant temperature sensor I will replace tonight. After that, I do not know what to do or think next. Any thoughts or ideas would be greatly appreciated. Thanks.