I have a 90 4Runner that only has 189 miles on a rebuilt 3.0 courtesy of Jiffy Lube. Unfortunately, this thing is running like crap! I've taken it back to my mechanic twice now and he has gone over everything he can think of and can't seem to figure it out. So now I come to all of you to try to get some advice on what to check next. So here are the symptoms:

idles fine
once in gear and moving it accelerates very poorly (no power)
once at a constant speed it starts to sputter like CRAZY!!!!
the sputtering is SO bad that it jerks the entire truck.
and i have to downshift to make it up a bunny hill.

I'm not the most mechanically inclined person in the world but I trust my mechanic. (hasn't done me wrong yet). He told me he has adjusted the timing and everything is right there. Said he checked over everything else and can't seem to find anything that would causing this. Any help would be great!

 

How about cam timing? Just a thought, if hes not familiar with these v6s its easy to miss that.......regards.....Rick

 

What exactly was done; complete rebuild or was it a rebuilt block he installed?

Cam timing can be a bear.

Poor acceleration can be the TPS or knock sensor.

 

My mechanic is very familiar with these engines as all he works on are Japanese imports.

When we got the engine it had 134K on it. Got the master rebuild kit from Enginbuilder and started there. New plugs, wires, vacuum lines, etc... with everything he did this thing should be purring like a kitten but its not.

Is there a simple way to check the cam timing?

 

I'd suggest you get your mechanic to come on here and post about it. Getting 2nd hand 411 isn't usually the best nor easiest way to fix a problem.

Lack of power suggests cam timing.
Sputtering suggests ignition timing.

Have the injectors been flow checked? Has the thing been put on a scope and ignition characteristics checked? Are the valves adjusted to spec? Timing set properly, TPS adjusted, etc?