wont accel over 1500 rpm

so my gf's 1998 blazer v6 over the weekend decides to quit driving normal. going down the road all the sudden it falls on its face and will not accel.vehicle will idle in park and rev up on the tach only in park. as soon as you put it in drive and begin to take off it spudders bad and wont go over 1200 to 1500 rpm. anyone had this problem?? thanks

Possible plugged exhaust or weak fuel pump.

exhaust is already gutted and im thinking its a fuel problem...fuel pump sounds like it primes up fine when start up

You need to get a guage on and check the fuel pressure then.
 
What do you mean "the exhaust is gutted"?

probably took the insides out of the cat.