I can't tell you what to check, but I can tell you that the situation you describe is not normal. I've spent numerous 10-12 hour days behind the wheel (literally) and while I, too, would kill for cruise control ,I don't find that pedal effort excessive.
And I have dual return springs on the throttle linkage.
Don't give up on the car - it isn't inherent... you've either got binding, or the wrong throttle cable bracket, or throttle return springs made for the Queen Mary, or...
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