gunning the engine can be simulated by three different actions, see which one has an affect...
1. wiggle stuff. Perhaps something is loose. Best culprit is the central ground connection or the point where the wire harness slips through the firewall. Also don't forget the battery's ground and the engine's ground strap.
2. sudden change to vacuum. Is the vacuum sensor in trouble? Do you have cruise control?
3. The throttle position sensor may be flaky or the wiring to it may be flaky, or the thing may just be dirty.
PS. And there's always the maligned trigger points. When where they last inspected and cleaned? They DON'T need to e replaced, that's for sure.