I have a 95 Rio Grande with a problem I can't get rid of. I just rolled over 183k and I have a engine miss. I've replaced O2 sensor, new sparks, coil, distributor, cut the cat conv. off, new exhaust....and it is still missing. Seems to be between 2000 and 3000rpm and usually in 4th gear....any ideas or suggestions what I should check next?