Its and 89 BII 2.9 4X4,
The problem is that sometimes not all the time but sometimes my idle will go up to maybe 3200 rpm or so and my foot is not on the gas at all. Most of the time when this happens when i slow down with the brakes the rpms go down to normal, or sometimes when its just idling it will be at like 1300 rpms or so.. where normally mine runs at about 850 or so... Any ideas or suggestions would be helpful thx.

 

I have the very same issue on my 89 b2 2.9 4x4 with standard trans. I was thinking my cruse control had something to do with it but not sure at all. If it happens more I will have it looked it but it seems to do it maybe twice a week or so.

I seen there is a mod you can do. Something about going to a local junk yard and find a TB off a newer 2.9? I dont know for sure. If I knew what to look for I will get to it. If someone can post that mod I'm talking about. I dont even know if I have the small TB or the larger one.

Anothe question I have is Marvel Mystery Oil. I have used this stuff in my Cessna 150 aircraft for over 15 years. My A&P tells me its the best thing you can use in a air cooled motor. I have used it is my B2 for over 2 years now and have had great luck with it in the crankcase and the gas tank. When I first got this used b2 it had 70k miles and burned a quart of oil in just 1000 miles. Now its down to one every 4000 miles and still has a small rear main leak and tiny leak on each valve cover.

The only thing I know for sure is I'm on vacation in Las Vegas and the wife is trying her luck while I'm enjoying a killer view of the city paying WAY too much for laptop internet access (10 bucks a day) & wishing I was home playing with my B2

 

I would start by checking for codes and vacuum leaks. If it does it when you apply the brakes the booster might be leaking when you press on the brake pedal, you normally can hear a hiss in the cab.