Car won't run past 60mph

67/6barracuda said
Just so I understand that I may have it backwards. I thought at full throttle I should have full throttle pressure. This means that the throttle valve is pushed in the valve body all the way at full throttle. Is this not true? Please explain...where should the throttle pressure valve be at full throttle? I just put 8 quarts of fresh fluid in and still need at least another quart added before I test drive.

Yes, what you are asking is true, and at full pressure the trans probably won't upshift until really high in the RMM's if at all for the 2-3 shift.
Actually the lower pressure the sooner the shifts, so you really need to sort out your TP control linkage instead of trying to mod the trans for a messed up linkage.