I have a Volvo v70 2002 2.4 auto engine runs drives ok on driving it runs a bit lumpy fuel down to about 15.9 mpg thanks

Has it ever been tuned up ie. Plugs, wires or boots, filters, and injection cleaning? Check the tire pressure, under inflated tires are the #1 cause of poor mileage. Also consider fuel quality and additives that don't contribute to combustion. I hope this helps, Take care.

With a carby the problem will occur because the engine is trying to work when you place it in drive and go nowhere ( same as putting a brake on the crankshaft). Use more choke or set the auto choke to run slightly faster. IE close the throttle butterfly more to increase engine speed. It all has to do with the fuel trying to evaporate in the carby and icing up the working bits and you need extra fuel to overcome this problem for a short term

Lead foot, tire pressures, stop /go driving. AC/poor compression, Trunk full of sandbags, transmission slipping, Wheel bearing friction, Brake shoe always on, etc.

You need a full service of the auto transmission. Check the oil condition for burnt smell.
The oil may be burnt out and fails to lubricate when temperature goes up.
But most likely the gear gaskets or gear teeth are worn out.

replace lambda probe expensive but it will run ok after that, i dont know if you know how they work so here's a brief: lambda tells ecu how rich the exhaust gasses are, ecu ajusts fuel input as neccasery eg lambda says not anough fuel ecu puts more in and the other way round.
so if your lambda is covered in **** when you get it out just clean and put it back, if it looks clean enough it needs replacing!! jezza

sounds like a broken wire, but i cant say where, on ignition, fuel pump, under dash, quik scan could save alot of time an money

You need to take it to an authorized dealer for OBD-reading and see what's wrong.

if this around town then this is probably right as it is also an auto.

Doubtful. The K&N air filter is an aftermarket part which isn't compliant with standard factory parts against which those recommended MPG are tested.

The tyre pressure sounds too high for a car that size also, it would be worth enquiring with a main dealer what the reccomended pressure is.

Also your own driving ability comes into equasion too. Heavy/constant braking can affect it, having the air con witched on affects it etc etc.

All of the above combined would make a pretty big difference to your MPG.

volvo s80 y reg 2.4 runs ok little bit lumpy tickoover when warm but very loud whistling noise take dipstick it stops but very big suction from tube not pressure it is not breather box under manifold