The summer will be back with the triple digits and we feel it since a few days. The idle surge I observed last year is also back. This issue was gone since last fall.

It only happens when the car is stopped and the engine running at idle is very hot. Suddenly it goes up to 1150 rpm goes back to 750 and stabilized at 850. I am also wondering if the situation is not worse since I installed the JB+ even causing from time to time some perceptible vibration that go away after a few seconds.

I am wondering if it is not the change in the gas blend for summer that we receive from the California refineries that is the source of the problem.

Mine is a manual so it has nothing to do with the downshift of the AT.

Anybody else has ever experienced this problem?

 

I see a lot of posts about idle surging and half dead fuel pumps.

Perhaps try looking for broken vac lines/leaks.