2000 Boxster intermittent stall issue

[daysalw]

My 2000 Boxster 2.7 used to run rough, and would occasionally stall while idling at intersections, and, after a while every now and then at rapid acceleration it would just flat out shut off for about two seconds and then take off again. It also used to lope at idle, going from 500 to 1,000 rpms. In the morning, if I did not let it idle roughly a while until it smoothed out, it would stall and run rough until I left it idle for a while. I cleaned throttle body and replaced the MAF, and all spark plugs, ignition coils, and spark plug tubes. The car now idles without loping. However, it still stalls intermittently at intersections and when pulling out, and every now an then there is that hesitation at rapid acceleration. When it dies when pulling out, I can just flip the key to off and then on, and it will run. On one occasion, it was like the car was stuck at idle, with no response when I pumped the gas pedal, and I had to turn it off and then on again to get the throttle to respond. I always use 93 octane, and have tried adding an octane boost, with no change whatsoever. Is this possibly an issue with the egas? I would appreciate any advice on this.

[thstone]

Assuming that the CEL isn't on and there are no codes pending, I'd start with checking the throttle position sensor and the fuel pressure.

[jvfante]

I've chased this intermittent stall or hesitation issue on my '98 2.5L MT 138k Boxster for several months and replaced all the usual items myself: plugs, coils, MAF, O2 sensors, fuel filter, cleaned Throttle body & checked fuel pressure. The car ran great, but still had the occasional hiccups when accelerating.

In desperation, I took the car to a local indie shop and then to the Santa Barbara P- dealer and neither of them (and their fancy machines) could figure it out. They did take my money though and wanted another 4 hours to check my wiring....

Then, thanks to a suggestion to check for vacuum leaks from "itsnotanova" (via his Plano, TX Porsche dealer), I found the culprit to be a slight leak at the coupling between the top breather hose and the AOS. I fixed the leak and the hesitation is no more.

Many thanks to Woody & the guys in Plano.