Toyota Repair: toyota 4 runner repair, path of least resistance, toyota 4runner

Question
I have a 2000 toyota 4runner 3.4 liter with 150000 mile its giving a random mis fire code idles rough when cold wont get over about 2500 to 3000 rpms and if you give it alot gas it backfires through the throttle body and ideas? I have replaced the spark plugs and fuel filter what do i do next ?

Answer
I would suggest having your catalytic converter checked out. You cannot accelerate the engine because the exhaust has no where to go so it is backfiring out thru the path of least resistance (the throttle body). You also may check your EGR (exhaust gas recirulation) system checked out. If you perform your own repairs I would suggest unbolting your exhaust pipe from the exhaust manifold. This will let the exhaust escape thru the proper channel. Start your car now and see how it runs. It will be very loud but it is a free way to diagnose the problem.