I have an 89 gta 5.7. Out of nowhere it started loping really bad while driving to where it will die. It will start ,sit and idle. I can even rev it up all I want but nothing. The minute I shift to drive and take off it will just act like out of fuel. This car is like new 20 k miles. Plan to put fuel pump in but my fuel gauge never goes below about 35 to 40. Any ideas?