I recently had to have my car dyno tuned because it wouldnt pass emissions testing here in TN. After the tune, this problem has gone away but has been replaced by a more agrivating one. The idle rpm is erratic. It will sit and lope nicely for a little while with the cams talking to ya nicely and then just change, normally idle rpm going up and then back down and up again. Not a big change at all but never the less it is erratic. The car dyno'ed at 339.9 rwhp and runs GREAT except for this problem. The engine light stays on all the time, which is not unusual, its been coming on and off ever since I started modifying the engine. It just normally goes off by itself after a couple of days. There are no trouble codes on my diablo. Think maybe this is the same problem I had before, just manifesting itself differently after the dyno tune? Fuel pump maybe? I also seem to notice a little rpm change just cruising like the car is surging just a little. I am going to post the dyno sheets as soon as I get a scanner, the A/F ratio seems pretty erratic on the pulls to me. Any ideas guys? By the way, the car passes the emissions testing after the tune.