When i'm driving and I get in like 4th or 5th gear my 4runner will start lurching forward a little bit every few seconds, just enough to be annoying. It only happens when i'm on the gas, it does not happen when I'm deccelerating. Does anybody have any idea what the problem is?

 

it could be your clutch slipping, it may be time for a new one

 

timing, plugs, o2 sensor...
have you checked for any trouble codes?

 

I had that problem but it was in all gears, my cap and rotor were toast. The rotor was worn down so far I could look at it the wrong way and it would fall apart heh

 

could it be something to do with some aspect of the fuel system?

 

I'd look into the fuel filter.

 

i'm bringing it to a mechanic tommorrow, i hope it's not something to bad.

 

I had something like that happening for a while and finally got it fixed. Took it to the mechanic just last week he ran the code and it was misfiring and it was a cracked spark plug, fixed the problem completely.

 

I think your truck has bronco syndrome...