Engine runs rough

Recently I was driving down the highway at 70 mph started going up a hill and my engine just bogged down. When I got to the top of the hill I feathered the gas a little bit and it got right back up to 70. On the next hill however it did the samething but this time it would not get up to speed. I pulled off and stopped at the gas station. I checked all my fluids ended up adding half a gallon of coolant. I started the truck and started on my way. It would not go over 45 at this time. I stopped at my friends house and then on my way home it continued. Everytime I got on the gas the engine just bogged down if I had to estimate it was around 3000 rpms. I went to my buddies shop and he put the scanner on it even though no lights were on. It came up with a misfire on 7. I had just changed the plugs and wires two weeks prior. So I changed the cap and rotor this made the truck run worse. Next we noticed the coil pack had a crack in it so we changed that no change in the way it ran. Also changed the MAP sensor and nothing worked. Used fuel injector cleaner in the gas and let it idle which it did very rough. Tested the compression on two cylinder results were 105 and 120. Then tried the fuel pressure which was 50 with very little drop off. Still tried ether just to check and whenever we sprayed the ether the engine quit. We are now stumped. Any ideas would be great.

Have you done a complete compression test to see where the engine is mechanically on all cylinders? If you have 2 that are 120 & 105, that is a large difference and could very easily be why it is running poorly.If the cap/rotor made it run worse, double check the firing order (1-8-4-3-6-5-7-2) It is common to mix up 5 & 7.

So I literally have been having the same issue with my truck it will get to opperating temp and all of the sudden have a rough/misfire idle and I did coil packs wires plugs idle control air valve tps sensor air filter new connectors and s fuel pump and regulator turns out all it was is the PCV valve on bot sides make sure you put in the correct ones in! Oreilly’s helped me find the correct ones and told me which side to put them in and I no longer have an issue truck starts and runs great now. Passenger side was all gummed up and drivers side was wrong pcv and truck runs like a beauty now!

Great addition to this thread! Please feel free to help out whenever you are on the site :)

Cheers, Ken