88 Fox no power after 3500RPMs

Did you check ignition and camsfaft timing. Also did you check the cat to see if it's plugged?

What is the best way to see if the cat is clogged with out putting a new one on?

What is the best way to see if the cat is clogged with out putting a new one on?

If the exhaust manifold overheats, the cat is plugged.

Do Fox's use digifant I? -Check O2 sensor, and temperature sensors.

'88 Fox should be CIS-E. Fox didn't get the Digifant until a couple years later. Though I think CIS-E does have an O2 sensor.

Will it rev above 3500rpm in neutral? If so, my guess is that the problem lies in the fuel system. If not, could be anywhere. Sorry that's not real helpful. :(

Have you replaced the spark plugs/wires/coil/distributor cap recently?

If it won't rev in neutral either and/or is struggling to rev, your ignition timing is probably way off.

I am replacing the cat tonight and hopefully that fixes the issue also it will not rev any higher in neutral

If the cat doesn't do it, check your ignition timing.

The cat does not seem to be the prob does anyone know about the coolant temperature sensor?I see three sensors on the thermostat housing which one could be the prob if any?

coolant sensor isn't going to affect revability. ignition timing is the likely culprit.

Ok, so I looked it up in the Bentley. Poor performance under full throttle could be caused by:

Weak ignition spark (had a tune-up recently??) Intake restrictions (replaced the air filter recently??) Air flow sensor flap binding or faulty Inadequate fuel supply (replaced fuel filter recently??)

In any kind of "guess and check" automobile troubleshooting, you generally try the cheapest things first and make your way up to the most expensive ones until the problem goes away. In this case, I'd say

Just IMHO :)