Idle is only sligtly rough, but Engine surges when throttle is opened slightly. This happens when driving slow and steady with engine warm. I can duplicate with air cleaner off and hand open throttle. Spray from both injectors is even fan and can be seen to increase and decrease. No Tach is present to log RPM. I have change throttle position sensor trying to solve this. Also Cap/Rotor, wires and plugs as part of regular maintenance. All Looked OK but changed any way. There is no fuel pressure gauge or place to install one that I can see to determine fuel problem.