Throttle Spring

[groomvroom]

Picked up a 4.3 Chim the other day fpr a job, drove very well on the 150 mile trip home apart from a very heavy accelerator peddle. Arh still has all the springs on the throttle mechanism I thought, opened the bonnet, nope just the one long spring. Anyway, the base idle was off and the stepper motor was filthy so I popped the plenum off and gave everything a good clean and a reseal (which sorted everything). While I was at it I checked the throttle cable, all running smoothly so not that, reconnected the cable, all bloody stiff again, OK scratching my head now! Checked my Griff which still has both springs on, nicked one to try on the Chim and hay presto! Normal peddle action. Seems the spring fitted was too heavy. While the Plenum was off I notice it had "4.5" in black marker under the throttle body so I am guessing it’s had a new plenum. (as to why I cant fathom, any performance advantage in a 4.5 one?) Did the later Chims maybe have a different peddle arrangement that needed the heaver spring?