1997 Villager stalls but does not go dead

I have a 1997 Mercury Villager, starts on the first try and runs fine for 15 - 20 minutes; then begins to lose power (bog or stall). Van engine does not die but tach will not go up when accelerator is pressed while in drive. If you shift to neutral and press accelerator the tach will go up and engine will rev. If you turn off switch and restart immediately it will run fine for 3-5 miles then begin the same behavior. I have cleaned gas tank, replaced fuel filter, and MAF sensor, fuel pump replaced about 2 years ago, car was used very little for 6-9 months and trying to bring back into service as secondary transportation. I was thinking fuel pressure regulator, or check fuel pressure check, then distibutor? Any more ideas or help on what to try next?:runaround:

I would start by taking distibutor cap off and checking the rotor to make sure the screw has not loosened on it, and also tale the cover off that covers the optical sensor (Camshaft sensor) and look for any brown dust on it (if there is dust the bearing may be bad in dist.

Check coil also that may be losing spark when warm.

I would also tape a fuel pressure tester to windshield and observe fuel pressure while driving to start eliminateing possibliity;s.

How many miles on vehicle?

How is the transmission shifting before this happens (harsh or hard shifts, etc)

Van is an old warhorse it has 261K on it but has served us well. The screw in rotor was fine and I removed cover over optical sensor if I have gone far enough and saw no dust. Will move on to next steos tomorrow and keep posted.

another possiblity is the TPS (Throttle Position Sensor). These are wear items and do fail.

97 Mercury Villager back on the road running great. Solution to the problem was odd to me but I am no expert. Gas cap was bad; not breathing properly and creating a vacuum not allowing fuel to get to injectors etc.... starving engine for fuel. Thanks for everybodys help.:grinno:

97 Mercury Villager back on the road running great. Solution to the problem was odd to me but I am no expert. Gas cap was bad; not breathing properly and creating a vacuum not allowing fuel to get to injectors etc.... starving engine for fuel. Thanks for everybodys help.:grinno:

Glad to hear you got it running. What determined you to change the fuel cap. At least cheap and easy fix. Thanks for posting fix.