IM out of ideas for my 96 Pontiac Grand Am

Ok my car runs, starts, idles, just fine, but when I give it gas it falls on its face, it's like it just stops getting gas and stalls, then it will get gas and keep going and then back to getting no gas again now when im going faster it reallly doesn't do this it seems like when its under a load is when it does it. It has 206,000 miles on it it is a 2.4 twin cam and it has all new sensors, new sparkplugs, new intake gasket, hard codes none, soft codes none, new fuel pump, new filters, checked for vacume leaks can't find any, put gas treatment through it, put fuel injector cleaner in it, took it to a dealer and they ran tests on it all they told me is that it had a leak in the intake on the second and 3 cylinder so I had my mecanic replace it, it didn't help so maybe one of u can