I have a 91 4runner, every morning it takes 15-20 seconds of cranking the engine to finally start...but when it starts it's a really rough idle and then about 5 seconds later it clears up and runs like a champ...I've done timing, cleaning the cold start injector(but I haven't tested the injector yet) and It has a new full tune up...I am very familiar with cars...I'm a mechanic at a dealership and I think it's my cold start injector but if u have any other cheaper ideas let me know..
Thanks

 

Check the Cold Start Injector Timing Switch. It is what contols the CSI.