why does my car hesitate and cut out when I give it gas on 2003 Lexus GS430

At first my car would hesitate when cruising along and I would have to accelerate quickly, but all of a sudden it does it now when just starting out slowly. The vsc and check engine lights have come on several times, when climbing steep grades it seems. I remove the battery cables and the lights clear until I put a load on the engine. The lights are not on now, but it cuts out all the time when applying gas. The car starts and idles fine. Thank you!

Asked by for the 2003 Lexus GS430
could be mass air flow but the code would help
I cleaned the MAF sensor with MAF cleaner and replaced the K&N air filter with a regular one. This made a tremendous difference, but when idling, if the accelerator is depressed quickly there is a definite hesitation at first and then the engine revs normally.This also happens when driving and the accelerator is depressed quickly for increased speed, there is a momentary hesitation, but then the car responds smoothly and with the power it used to. Any suggestions? Thank you.
1 more answer , 2 more comments
Have it scanned when the light is on for better information and then post the codes so we can help.
Thank you, I'll do that!
Good deal