My 1994 Jeep Grand Cherokee was running great for years, then one day it would not start. Mechanic checked spark - none - he replaced the Crank Position Sensor - got spark. Changed plugs and distributor cap while he was at it.

Since then, it starts, but after about 5 minutes (of just city driving) it will then sputter and choke, backfire some. After it goes through this caughing period for a few minutes it then runs fine again. This happens every time.

Could it be a bad CPS installed?
Or other problem?

The muffler rattles a lot too, not sure if the catalytic converter is making the rattle noise and if that could be related (?) or not.

Thanks for any help,
- D

If the CAT is bad it could be your problem, but I would start with replacing the CPS again, seems to be your problem. Remember to disconnect the battery while replacing.

Other things to look at:
1. O2 sensor
2. Throttle position sensor
3. Air idle motor
The last two are on the throttle body. Air Idle Motor (AIC) can be taken out and cleaned