i have a volvo 5.7 gxi-a that recently has devloped an irradic idle and loss of power. The compression is good, seems to have good spark, timing seems to be set right, fuel sample is good and pressure is good. Motor seems to have a shake at idle and the shake gets worse under a load. According to the tech mate there are no codes. I was thinking ignition module maybe going out? but i really have no idea other than that. Any suggestions. I can tell you with the tech mate if you force the base timing to 8 degree the motor idles right up to 1000 and seems to run very smooth. Under normal timing it shakes at idle and seems to run much rougher when u rev it up with no load.