problems under low rpm

Hello and thanks in advance for any advise.
I have a 97 SC2 with 150,000 miles. Never had it in the shop for engine work. Conditions.
With Air Conditioning on - Engine starts difficultly (good battery, connections etc.) I usually try the engine once, turn it off and then once again and it works.
Under slight lugging conditions it jerks and will even activate the "Service Engine Soon" light which will turn off after I turn off car for awhile.
If I'm on cruise control say going 55 and I'm on an uphill and hit the acceleration button quickly 5 or 6 times, it will try to accelerate but then kick the cruise control off as it bogs down.
What I've done so far.
Fuel injector cleaners that you add to the gas.
New oxygen sensor (upper)
Any ideas?

first the SES light is it steady or blinking? a blinking SES normally means a misfire. ether way, i can help you more if you get the codes read. next, the acceleration on the Cruise control works better for me to hold it down until it gets to the right speed. otherwises, the brake/clutch switch are common cause for the cruise to cut out, less likey the VSS is bad. when was your last tune-up? check the plugs and fuel filter, fuel pressure too if you can. if your idle is hig too, you may need to clean the EGR