Engine Rev Limiter

I have a question, My 2001 Ford Ranger has a v-6 4.3 l. engine in it and when I mash the gas down in Park Position in Transmission the engine tach will only go to 3000 rpm's and engine then goes to surging, is this normal, when I lift offf the gas it goes to normal idle. Also my check engine light is on, truck only has 20,200 miles on it, I knew better than to buy this truck...............

first of all your ford better not have a 4.3L. thats a chevy motor. you have a 4.0L. that surging is the rev limiter. nothing wrong there. take to auto zone or a parts store with a code scanner and then post the code here for help to fix!