I have a '99 4runner with 165K miles. For the past couple months I have noticed rough "warm" starts. My 4runner starts fine in the morning and after it has sat for periods of time and cooled down. However, when I run errands or am turning my car on and off multiple times it has a tough time starting. I have pulled the Idle Air Control valve and cleaned it, and it did not help. (However, it could be a bad valve) Does this sound like an idle air control valve to you? Or possibly a fuel filter problem? I do have exhaust problems because someone cut the catalytic converter off my 4runner while I was at work. I put an aftermarket cat on. I also recently had to replace my radiator, flush the cooling system, and flush my transmission. Let me know what you guys think. Thanks

 

Sorry to hear about your Cat getting ripped off, i hate thieves.

As to my thoughts on your warm starting issues maybe it could be O2 sensors. When your engine gets cold it bypasses all your smog equipment so it just dumps fuel without input from your MAF, O2 sensors etc. When your engine is still warm it takes input from them and something could be starving your engine of fuel. Maybe clean your MAF with appropriate cleaner and inspect your O2 sensors, that would be where i'd start.