ok so when i got my volvo it was winter and cold engine ran very strong. lately i have finally done complete tune up, wires,plugs(ngk)cap and rotor...smoother engine now. i replaced fuel filter and air filter, engine runs well as it has gotten warmer out i have noticed a hesitation under part to moderate throttle, full throttle sometimes.....feels like a little rich in a carbed engine. i thought fuel pump but it runs very strong when cold, engine warms up then it starts in. still runs fairly well and reliable...cruisin at any speed i fine just acceleration problem. i checked for vacuum leaks cold and hot with carb cleaner none found. i heard fuel pressure regulators go bad with high milage so i replaced it. it actually diminished the problem but not gone. i am thinking temp sender for ecm? but i don't want to throw alot of money in parts at it. any help would be great.