Compustar kills engine on scion tC

Alright, here's the problem with the install on a 2005 Scion tC: The Compustar has a remote-start saftey feature called "Reservation Mode". You pull the ebrake up and alarm takes over and sends signals for ignition and accesory so you can pull out the key and the engine remains running. Then you get out and close the last door and the engine shuts off and locks all the doors and arms the alarm. The problem is, when the alarm is supposed to take over, the engine rpm's dip down and the engnie dies most of the time. Not always though.. Also if i give it gas to keep it alive, it will run about 150-200rpm's short, making the car idle rough. So I'm thinking it's a tach issue, but we tried the black tach wire from the ecu pinout, we tried gonig directly to the uncommon wire on the coilpack, we tried even not using tach at all and using alternator sens.. The problem is still there. We even tried another brain (CM3000v2) and that one does the same thing. (Same unit as I have now). The alarm model is Scosche/Compustar SC2W900FMR (3000). We've tried calling Scosche and Compustar, nothing they recommended has resolved the issue. We're just baffled. If anyone has any idea what could be wrong, I'd appreciate any help that can be given. -Jason (Sorry if the post sounds remedial, for the most part I just crossposted from the Scionlife forums, but since most of them aren't installers I had to be more specific.)

Other than the problem described above....does the unit work properly. Does it start the vehicle? Can you get in and drive away? Are you using BOTH starter wires? Keysence?

Yes, the unit can start the car fine. so did the autopage we had in the car before (the autopage didn't have this rpm/idle problem). We tried two brains as well. I'm not positive if he used two wires for starter as I didn't wire anything myself. I know we've tried the transponder for the keysense in two modes, one to always send the key in the ignition on top of the one from the module if the alarm was taking over, and we also tried the setting to switch to one key or the other. I'll try to find out if we're using two wires for the starter. Other than this one problem, the unit is perfect. Right now he has the starter function disconnected and the car has no sign of the problem.

Yes, they are an authorized dealer for compustar/autopage. He does good work, and none of the guys he knows from other shops knew what the deal was. The consensus is my scion is posessed, heh. Anyways, yes he's a professional installer. We were getting tach from the data-conn already :( We're both stumped.

*Bump* I apologize, but still working on figuring something out, looks like both wires for starter.. I don't think it's in that part of the logic anyways.. seems that its when the brain is supposed to take over acc/ignition to energize those wires that something is losing power, but we checked everything and it all remains full power.. *sigh, i'm boggled.

Silvercivicsir, Did you use a relay or a diode with them y'd off? we tried a relay, we didn't try using a diode with them y'ed off.

not sure i just installed the scosche piece in the scion tc and all worked fine no problems with reservation mode. as stated you are using both starters? and both ign? and you made sure the car's keysense wire has a neg input when the 900fm tries to take over??? check this with a meter or even a light to make sure its getting ground when you try to make it take over. the only other thing i can think of is an immobilizer problem. same deal make sure this is working right. what kind of bypass did you use?? you say it starts the car fine normally right?? so it has to be something thats going on after that need to be looked at.