Did much work on the engine of our TP Elite sedan early this year & it went well. But now it is rough & gutless when driving forward. Yet is seems to drive OK in reverse (trans is auto). It starts perfectly, seems to idle OK until driving forward. It lacks power, seems to run on less than 4 cylinders & backfires through the inlet system if you use too much accelerator. When warm is seems to cruise OK with little throttle but it is rough & lacks power on acceleration. Any ideas to what this problem may be?

Distributor?

i would check the dissy plug for corrotion . timing. had a tr with similer problem was the fuel pump.

How's the fuel economy?
Could be the temperature switch for the ecu.

Think these cars have one, never really played with the EFI Magnas much.

Crikey, thanks for the quick replies. A new distributor was fitted when the engine was overhauled in September last year. Also fitted a new ECU temperature sensor at that time.... & I checked it too! (it's located in the inlet manifold water jacket on the underside of the temp gauge sensor). The LT plug to the distributor was replaced new with boot in June last year. When time permits I will check the dissie for moisture. Then I'll pull the plugs out to check along with a compression test. My first thought is maybe there is some interaction between the auto trans & the engine ECU that might cause the problem.

Also the fuel pump & filter were replaced new in January 2010 along with a good S/H fuel tank which had little rust inside to speak of (the original was badly corroded after sitting unused for awhile). Reconditioned fuel injectors were also fitted.

a couple night checks. look for spark arcing.around coil and leads. if you can go around the block and see if the exhurst manifold is glowing.

When you say fuel filter, just to confirm, you mean the one in the tank when you did the pump?
Or did you also replace the one in the engine bay?

Have you cleaned the MAF?

The fuel filter I spoke of replacing was the large one in the engine compartment attached to the firewall, driver's side. The fuel pump had a pickup filter that was replaced as part of the new fuel pump. What is the MAF?

Ignition timing - do it by the book. Check for advance working correctly.
Ignition leads -check for resistance values.
Ignition coil and power transistor - can cause these symptoms when breaking down.

its inside the air filter (metal canister)
and has several functions to read
air intake, fuel regulation, temp ,

if any one of the elements fail
can cause your problem

especially hesitation under load

how old are the spark plugs

Checked the spark plug leads. Readings of 2.8 to 5 K ohms on multi-meter. New leads had lower readings so replaced the lot new. Both old & new are Bosch. The old leads are about 5 years old. No.3 lead gave an intermittant reading so it was breaking contact with movement. Got all excited that this might be the problem but no. Engine rough & stalling in drive. Checked the timing but that seemed OK. Checked the air intake hose - the large rubber concertina hose that runs from the air cleaner to the inlet manifold intake & found it had split underneath (out of sight). Replaced that with a good S/H unit I had spare & the engine now seems smooth & responsive in Drive. Will take for a test run tomorrow. Those large rubber hoses are expensive new if you can get one locally new (which you cannot) so I Googled the part MD093693 & found Parts Planet in Chicago USA. They have it listed for $102.90 which is less than half the price I paid in Adelaide for a new one in 2002. Does anyone know about this site www.parts-planet.com/?

PROBLEM FIXED!
Drove the Magna up on the ramps to do an oil change & it ran perfectly. So replacing the torn rubber concertina inlet hose that connects the air cleaner & MAF to the throttle body fixed the problem.

SYMPTONS EXPLAINED
When Reverse was selected, the engine would move in such away that it would close the tear in the inlet hose.
When Drive was selected, the engine moved in the opposite direction on it's mounts & the tear in the inlet hose opened up. This leaked air into the inlet system, bypassing the MAF in the air cleaner housing & upsetting the engine management.

Thanks to all who gave advise.