High Speed Miss
 

I have a 98 Tiburon 4 cyl manual with 130k miles. It somewhat recently started having a high RPM miss. If you hold the gas pedal down about half-way, the car seems to be OK. Step down any harder, and it really misses. Speed will go down to about 35 MPH if you don't let up so the engine will catch back. It's the same in all of the gears. Have put on new plugs and wires, fuel filter, Sea Foam in the gas, and air filter, all with no results. I'm a hack mechanic, and it just doesn't make sense to me. No check engine light has ever appeared, and the light does work. It seems like it's flooding out when you really give it the gas, and that really isn't possible is it?

Have you confirmed there is not a possible exhaust restriction, sure sounds like it is !

Thanks for the suggestion. I drove it this morning on a desolate road and kept it floored for about 3 miles. It was in second gear and wouldn't go over 20 MPH. It coughed and sputtered, and when I let off the gas to about 2/3 of the way down it perked right up and red lined at about 65 MPH. I ran it for another couple of miles floored and the check engine light finally came on. I'll check the code tomorrow and let you know. Thanks again, Nelson