van lacks power, seems to be wide open throttle, stays in downshift or briefly shifts to higher gear to about 45mph. no engine lights or codes. tail pipe and converter look ok no damage. pulled wire on upstream sensor, threw a code, reset, still lack of power. 164k miles driven 20 miles a day, just did minor tuneup, checked for broken vac lines, fixed 2 vac line for ac. engine idles good, revs ok at 1/4 pedal then bogs down as if grabbing for air. Any ideas?