I just purchased an 84 T-Type; it is running very poorly. although it did make a perilous 400 mile journey home! First, the exhaust is a diaster; it has Kenne-Bell headers and up-pipe, downpipe and no CAT with a cheap turbo muffler and ratty 2.5" pipe dumping about under the back seat,(with pipe curved down causing horrible sounds and resonance)! Second, in terms of symptoms; it sometimes stalls at idle, (like when put in reverse, or after pulling off freeway), surges at speed,(freeway), the "service engine soon" light comes on for a minute or two, then goes off, and once even backfired! The seller told me he'd just installed an O2 sensor of no-name brand, could this be problematic? Other mods are; Kenne-Bell Ram-Air cannister and scoop with K&N filter, 87 coilpack, 160 thermostat, flex fan, Accel wires, TTA fuel pressure regulator, adj. wastegate, shift kit, and the aforementioned KB header system. Also, I should note, I put an XP-240 Scan tool on it and found no trouble codes!?! The car also is suppossed to have a KB stall, and on the scan tool, I noticed the TCC reading would lock/unlock/lock when going about 50mph, then letting off and coasting to a stop. There were two owners prior to me; the original kept scrupulous records, the seller advised, "he kept the paperwork, but it was of little value!" Well, in perusing this paperwork, I found the installation for the KB headers; it claimed that the headers were so efficient they could cause the OEM O2 sensor to not "light-off" as their efficiency lowered the exhaust gas temperature. This in turn, could signal the engine service light, and even cause the ECM to operate in open loop in the "limp home" mode! The fix, KB claims is the install of an heated O2 sensor, is this true, or has anyone had experience in this matter? I absolutely love the Turbo Buicks, falling "head over heels" in junior high school when they first appeared on the scene! However, as my first "Hot-Air" car, it is proving a little disappointing! Any advice is desperately wanted and needed, thanks guys! p.s.-the A/C also isn't engaging on the scanner.