Well Kev me Plus 4SS in disguise developed a cough and splutter on light throttle loadings, when i then put the boot down...... pops, bangs and stutters before we got lift off. Knew it wouldn't be plugs, leads, dirty fuel and the likes so suspected a field sensor and gambled it might the throttle position sensor. I decided to start here and the realized it was a modern Hall Effect type not the variable resistor / rheostat job which meant checking the voltage at the ecu, so i initially took the easy way out and unplugged the device to inspect the plug socket connections with a mag'glass, they looked a bit secondhand so cleaned 'em up and hey presto, throttle response back to what it should be. Ive done a couple of hundred miles and all seems ok.
So, if you are on Jenvey throttle bodies, as i am, you probably have the Giles and Penny TPS. It looks first class quality as does the moulded connection plug but the connections had become a but grubby, sufficiently grubby to create this issue. It does easily unplug for cleaning. It will probably save you silly money should you need to get the help of a dealer , who may not have experience anyway and bill you for many hours of fault diagnosis.
