1990 230TE Intermittent difficult starting and stalling

[Alan230TE]

My 1990 230TE (140000 miles) has an intermittent problem starting from cold and hesitation from idling, almost stalling. It can og months without appearing but then be evident for weeks. I cannot decide if it an ignition problem or an injection problem. It is a mechanical injection system with an electronic overlay. Sometimes starting from cold in mild weather can take some cranking over. I have replaced the temperature sensor which improved the ir but not completely. Never been a problem starting when it is very cold or very warm. The cut out described can be a second or less or sometimes cut out completely. You can be stationary say at lights and as you move the accelerator the engine starts to pick up but hesitates. Generally it picks up and hets through it. Sometimes too from cold it may not be there and after driving a few miles it iccurs. Any advice or known cures would be very much appreciated.