Rough idle, hesitation on acceleration, raw gas smell, rough running?

Now I have another question, totally unrelated to the vehicle and problem that I posted yesterday.
I have a 2003 Ford e-150 cargo van, 4.2 L engine. I'm having problems with what feels and seems like engine misfire. Plugs and wires all just got replaced, changed fuel filter and air filter, just had a fuel pump in December. There's a strong raw gas smell in the cabin while driving, and it is idling and accelerating really rough. Sometimes it will stall if I'm in D but stopped at a red light. There's some hesitation when I accelerate and loss of power and fuel economy. I was sure that it was the MAF sensor, and because I have tried cleaning it several times, and when I unplugged it there was no change in how the van runs, I decided to bite the bullet and replace it. So I replaced it today, and there's very little change in engine performance. There are no codes either. So I'm stuck at what it could be. Also will note that it idles fairly good when in park or neutral.

New car/New driver. How can I do everything the best way?

I'm a new driver. I just got my license and I'm 20 years old. (late. I know.) but, I recently just got a job at my local mcdonalds as a shift manager, so it's more money than I've made at any other job I've had. I was wondering is it wiser to go ahead and get a new car or should I get a used car? Regardless, I'm getting a car from a actual dealership like Honda, Ford, etc. I don't like nor trust the "buy here, pay here places" and I'm a tall, bigger guy, id have to get an SUV. Which suv(s) are cheapest on insurance?

Ford Credit Late Payment?

Unfortunately I forgot about a Ford lease payment that was due the 24th of June. Considering I scheduled the payment after hours, the next available day isn't until the 3rd of July. Therefore my payment will be past due for 9 days. Will having the account past due for 9 days effect my credit score even if the payment is not 30 days late?