So my 01 Bravada did this some time ago but stopped about a year ago but did it again yesterday. When I used to commute about 1-2 times a month it would be driving then you would feel a "stumble" at 30+ miles per hour and it would do it every so often until I shut it off and restarted. But then it would not do it for months. I put in a Skip White distributor about a year or so ago due to a cracked housing on the factory one and it never did the stumble again....until yesterday. On the distributor I left the original electronics in it but am using an AC Delco cap and rotor and have never had an issue.

When it started I was on my way home so I grabbed my phone and fired up Car Gauge Pro and when it did the "stumble" it got like 14 or more misfires with multiples in each cylinder, then they cleared up. It would do it about every 3-5 minutes and each time it would show numerous misfires then clear up. I pulled over after it did it a few times and checked for codes and nothing came up (I do have a recurring Secondary Air Injection code that comes up from time to time, but it was not there - yes I know i need to fix that). No misfire code of any kind. My timing is within spec (about 0.08 degrees), and the motor has no other issues.

I shut it off and then restarted it, and it has not done it since. If it follows the pattern it won't do it again for months.

I did a search and couldn't find anything but admittedly might not have used the best search terms. Any thoughts on this one?

 

It may be impossible to diagnose or tell when it is fixed until it starts exhibiting the problem more consistently

 

Thanks Les. I was afraid of that.