Weird driveability problem... Hmmm

This started tghe day i retarded my timing down to 8 for my blower 2 days ago.. I would drive through the gear with some to no boost and the motor would sound like its revin up, but wont be going nowhere.. as if it was bogging and making popping sounds under the hood .. then after a certain RPM, say 4000, it will cut right back on and take off like nothing happened.... Today driving around for a while, i noticed the problem went away after a half hour without a trace of what happened.. I could now rip through all the gears with no problem.. Now i would bet the problem is going to come back tomorrow.. what gives??

i am going to put the timing back to 10 to see if anything changes, but if it was a timing issue, wouldnt the problem be always, not by how long im driving????

ttt anyone knows?

is that a hard thing to replace and how much is one??? and how do i know for sure if thats it??

driving around for a while will fix the problem... but until then, it popps under load under the hood and doesnt want to move anywhere until a higher rpm sayy 4000, then it will cut on like nothing even happened and will fly through the rest of the gear...w eird