sounds like your armass airflow meter is going out, next time it happens , disconnect connection leave it off and restart , drive like normal and see if you can run it over 30mph, by disconnecting , computor reverts to a fixed operation ie ignores airmass, when mine when out thats what it felt like , surging and stalling, especially hot, or another possibility is overvoltage relay, its next to battery behing with a red fuse under a plastic cover = change it