engine lurching/hitching/jerking

[PaleRunner]

I have a manual transmission 99 4runner with just over 100k miles on it. I recently had the clutch, filters, sparkplugs, and air/fuel sensors replaced. A few days ago I noticed that the engine will lurch/jerk at random times. Basically, it is a spurt where the engine feels like it accelerates and then brakes for a split second. This does not happen while shifting gears - it usually happens while cruising between 1500 and 2300 RPM. Any ideas what this might be? I'm wondering if it is something wrong with my air/fuel sensor, which I changed just a few weeks ago.

 

[suprdtydvr]

I have a '96 with the 3.4L, manual transmission that exhibits the same symptoms. I have noticed that it seems limited to acceleration through 2nd gear. May be sometimes in 3rd. I am going to do some tinkering/ research and see if I can come up with some ideas. My truck has 163K on it. I will post my thoughts/findings here.

JR

 

[suprdtydvr]

I started with some simple things that needed to be done any way. Plugs, wires, air and fuel filters. Started it up and it ran great. No more missing at all. Lots of power. The plugs looked good as far as their color. Nice light brown color on the old plugs. Nice tight motor still at 163K. Single electrode Autolites came out and I replaced them with NGK dual electrode plugs based on the things I read here and that is the stock plug anyways.