My 97 F250HD surges when driven for the first few miles. It idles fine and runs ok above 50 mph. when warmed up the cel comes on and then it runs perfect. Turn it off and restart and the cycle starts over again. When cold and no cel it is almost undrivable. I blocked off the egr and no differrence and disconnected the tps and no change. Any ideas? Thanks

 

Could be a clogged/failing IAC, or the TPS going out. Pull the codes (there is probably stored history codes) and post em up.

 

I am at a loss with this truck. I get an act out of limits code (114) and it tests in the middle of the specified limits. I have replaced sensors with known good ones, tested the voltages in the harness. Everything checks out. How can i tell if it is a bad control module?

 

I think you were meaning the ECM...as control module..If so, it is located under the driver side kick panel. You'll need to use a 10mm socket, and loosen the bolt, disconnect harness, and remove from inside the truck. You can remove the screws holding the case open and have a peek inside. Look for burnt traces, failed capacitors that are either leaking, bulging, or have blown apart.

If you know the ACT is performing correcty, I would try several different things. With the 60-pin connector disconnected from the ECM, I would do a resistance check for various sensors. Be sure that those sensors are disconnected, as all you need to do is find out if there is wiring that is bad between the sensor and the ECM. This included the ECT, EGR, ACT, TPS, O2 sensors. I would test each when cold, then once you drive it and it warms up and the CEL comes on and the truck drives fine, do another resistance check on the sensors listed above. I would start with the ACT, sense that seems to be the underlying problem. Worst problem with OBD1 systems, is that 1 failing sensor, can create problems with other known good sensors or components, leading to unnecessary parts replacement of good sensors. It's a dominoe effect.