Maybe time to take 1994 SL600 to the Stealer

Took a break and now am going to start back on my SL600, either that or shoot it and put it out of her misery. It is still not running right, cuts out about 90mph and will not rev up over 4500rpm no power and shifts hard. Took it to acouple of indys who are suppose to be sharp with no real answers. The following is what has been done so far.
1-The injector harness is good( was replaced in 06)
2- Throttle bodies were rewired by Victor in NY
3-Rewired mass air flow sensors back to good wire
4-Removed injectors and cleaned them (they are working good)
5-New plugs
6-New fuel pump regulator
7-New fuel pumps and filter
8-New battery
9-New ignition module
The one indy had told me it was fuel pressure( that was why the pump,filter and regulator). Another said it was electrical. I have checked the injectors and I am getting voltage to the injectors and spark from the plugs. Neither one acted like the wanted any thing to do with the 600. If it is electrical after what I have done where do I start. Thank you in advance