2000 Pathfinder problems after accident and overheating

[junebug13]

Hoping someone can help. When a lady ran a stop sign, I hit her with the front of my Pathfinder. Front end repairs (hood, bumper, grill, etc.) were done, and signed off with the insurance company. Didn't drive it much, seemed ok. Drove 30 minutes on a hot summer day, 65-70mph. Got stuck in traffic (accident on freeway), and started overheating. Couldn't pull over right away, because of lane closures from accident. Drove about 5mph for about 10 minutes until I could exit. Added about a gallon of water and drove home (20 miles at 65mph) - seemed fine. After that, kept overheating. Garage replaced thermostat, then thermostat and waterpump, and did a test for head gasket (negative). Pathfinder also started sort of chugging and lurching at times, and tach jumps up & down.Another garage said it was a vacuum problem and did repairs, & also another test for head gasket (negative). This was a really great vehicle before, and after all repairs and tests, still overheats and lunges. Also, check engine light is on. When I idle at a stop sign the light flashes really fast, but stays on continuously when driving. Any help will be greatly appreciated!

[keelhaul]

Usually a flashing light means a misfire. If its not leaking coolant and thermostats are ok then it may be the fan clutch. when the engine is cool you should be able to turn the fan by hand and when it it is hot it should be more difficult to turn. If you can easily turn the fan when the engine is hot the clutch might be toast.
Modified by keelhaul at 8:45 AM 12/28/2009

[e2xx33]

Do you have the code for the check engine light? if not, go to an auto parts store like autozone and they will scan it for free. Then post the code on this thread