93 truck, 22re.....in neutral at idle it runs smooth, advance the engine to about 1500 to 2500 rpm and it starts to pop, misfire, cough.....any help out there. just put a new engine in and it was having the same problem before the swap.

 

fuel filter plugged?

 

I'll change it, anything else it might be?

 

check for vacuum leaks

 

You're saying it has happened across two engines, so fuel delivery seems to be the only common component.

Generally speaking, ok idle and sputtering/coughing at a non-idle speed is either ignition problems (timing, weak coil, funky plugs, seriously funky wires) or fuel delivery (weak pump, clogged filter, bad injectors).

Toyota pickups/4runners aren't notorious for fuel pump failures, so I didn't consider that a viable problem.

 

how about an egr valve? that or vaccuum prob , I would think...

 

vacuum/air leaks usually fiddle with the idle and less problems as you go up in RPMs.

Another thing I just thought of.. O2 sensor will do this, too. I would think you'd get a Check Engine light, but could be a few reasons why it didn't come on.

 

Tune-up? Vac leaks? EGR(unplug vac line to it and see if it stops). Check fuel pressure.