1991 Toyota Camry Misfires at upper end of RPM range (every

Starts fine and idles OK. At normal operating temperature, I put the car in 1st gear and take off (takes off fine on a flat surface). It will run fine with plenty of power until I get to the high end of the RPM band range it will then cut out (it doesn't pop or spit, sputter or jump - it just falls on it's face). If I let off the gas pedal, the engine starts running fine again. If I depress the gas pedal quickly, it will cut out again; however, if I very S-L-O-W-L-Y allow the RPMs to creap through the band range, it winds the RPMs without problems. Until I get to the next gear and the symptoms start over again. This will persist through all gears (1-5). Starting out on a hill is another problem. I have to double-clutch to get the RPMs up to get going and 'feather' the gas to keep it there. I end up running high RPMs at lower gears to keep the momentum. At highway speeds, an attempt to climb even a small hill requires me to downshift to a lower gear and again keep the RPMs very high.
I've replaced the Plugs, wires and cap combo, rotor, fuel filter, air filter and checked the dash codes (scans fine - no findings). I've also inspected the vacuum lines and electrical connections as well as reading hundreds of blogs and speaking with the local parts guys - the following is a list of remedies recommended: Idle Speed/Air Control Valve (ISC/IAC); throttle body carbon deposits; Mass Air Flow (MAF)(I assume this is a sensor?); Air Intake Sensor (IAS); Ignition Coil. Yes, I've added Heat, bought expensive gas, added Lucas gas additive/injector cleaner and have driven the miles necessary to make a difference - no change. One fellow even told me it was the battery - not enough amperage (I doubted this one). I understand the process of elimination, but the above recommendations can be quite expensive -that's why I've gladly donated to your site and look forward to your advice. Needing help in Alaska.