Pinging and A/C problems

I own a 1998 Dodge Dakota with 135,000 miles V6. It just started pinging about a month ago. The engine doesn't run rough or miss. It runs very good but as I excellerate it pings all the time. Next is at the beginning of this summer while running the A/C it works good until I start driving. It stays cold but when I excelerate the aif blows through the defrost vents or the heater vents as soon as I let off the gas the air comes out of the vents that its supposed to. Ok, what gives? Asking here first before I take it to a shop. Please help! Oh I have tried running higher octane gas and that does help the pinging a bit but it still pings but not as much. Thanks in advance!