The first step in troubleshooting a car problem is to identify the primary issue and when it happens, such as stumbling upon acceleration, and then take it through a question tree. Diagnostic sites, such as AutoZone.com or AutoMD.com, provide free question trees for car problems.
On AutoZone's troubleshooting site, users experiencing stumbling upon acceleration would select the Feel category, since stumbling upon acceleration is something you feel, followed by Hesitation on the next list. Next, the user would choose Acceleration and then Engine Compartment. The final page provides a list of possible culprits for the example problem of stumbling on acceleration.