I have a 99 Honda Accord v6 with an automatic transmission that has 153,000 miles. Recently, the transmission has started slipping. First, I noticed it when I was trying to get on the highway. I would press the gas and it was really sluggish and would barely get up to speed. Then I was coming home from out of town and I was going about 50 mph and tried to pass someone and when i gave it more gas, the RPMs redlined, but my car didn't want to go anywhere. Then the check engine light started blinking and I had to let off the gas completely before pressing the gas pedal again to make it shift. This continued for about 3 weeks mostly when I was trying to get up to speed while getting on the highway which made the check engine light blink. I took it to the shop, but of course they couldn't get it to do what I was talking about and they didn't get any codes from the check engine light. Now my transmission won't shift at all out of 1st gear. Any ideas what this might be?