I purchased a 1989 montero v6 for $400 because the owner had it to 3 different mechanics and none of them could figure out whats wrong with it. The last mechanic told them (previous owners) it was an ECU after about 5 hours of diagnosing stuff and not getting anywhere.

It will buck and midfire on partial throttle loads between 2000 and 3500rpms. If you floor it, it clears up.

also, at idle, it will miss on cyl #2. It fires when its cold, but has weak spark on JUST that cylinder. when it warms up, the spark dies completely, JUST on that cylinder. They tried a new cap and rotor, and even a new distributor (the old one was in the back). I made sure it wasn't the wire. If I pull the wire off of the sparkplug and ground it to the block, it will spark only within 1/8" of the metal, and even that is intermitten. anyone of the other cylinders it will throw a spark over an inch long.

Im ASSuming the miss on #2 has a lot to do with the bucking and surging at cruising speed.

other than that, it runs like a top and just had the head gaskets done earlier this year and has almost brand new suspension and tires! its tip top!