two strong items to check. The EHA valve itself - it's design is to act as a accelerator pump for this car. When you need more fuel quickly, then it gives you that strong shot of fuel and maintains it. Also, not sure if you have a throttle advance solenoid that controls vacuum used for aceleration, if so, on pass side behind/beside the washer bottle. Has vacuum lines going to it with a check valve somewhere along the line. Check valves could be cracked also, cheap fix.