1992 Ford Escort LX Transmission Problems

I have a 1992 Ford Escort LX with a 1.9L FWD automatic transaxle with overdrive. It has 161K miles on it. Bought it from a friend knowing it had a bad head, went to a salvage yard and got a good head from them, got the motor sounding and running nice, but am still having some minor bugs to work out. First, the tach in the dash goes to 3k RPM no matter how revved up the motor is.I know the motor is not canstantly running that fast. I have replaced the Ignition control module, crankshaft positioning sensor, and the camshaft positioning sensor. Did not help at all. Second problem, which is the most baffeling one is this, the transaxle. It goes into gear nice, but shifts late. Usually will not shift out of 1st gear until between 30-40 Miles per hour, sometimes will shift through the other gears late also, will not kickdown when pressing the accelerator down, and will not go into overdrive. It will down shift when approaching a stop light. I have replaced the throttle positioning sensor, idle air control valve, and have also checked the adjustment on the kickdown cable. The cable moves as far as it is suppose to be able to, so I know the cable is not hung up. I have compared the adjustment specs to the Chilton I have on this car and it seems to be set right. I also replaced the powertrain controle unit and the module, making sure that the numbers match identically. I am baffled as to why it will not go into overdive, will not kickdown when flooring the throttle, and shifts later then when it sounds like it should. I am also wondering if this has anything to do with my tach acting up. Since the Engine Light comes on and stays on, I hooked up an engine code reader, performed both the key off and the Key On Engine running scans but am unable to get any codes from either computer, original or replacement. Please let me know what you think it could be.