I've got a great oppurtunity to buy a 97 f150 x cab 4x4 lariet with a 4.6 for $1,000 bucks. The body is in great shape, but the engine acts a little funny. It starts up and runs smooth and sounds great, then all i have to do is touch the gas pedal and the truck dies right out, almost stalls and then is fine again when i let off. if i hold firmer presure on the pedal it stumbles and pops/backfires. I know the guy who owned this truck and traded it in and he was driving it just a couple months ago, so im not sure what to think. Could it be somthing like a mass air sensor, or somthing more serious? thanks.

 

Anyone have any advice at all? I'm supposed to have a yes or no for the seller by tomorrow. Thanks